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Patrick Fitzgerald -
Posted 12 months ago

WiFi for Train Communications

Communication Systems

  WiFi for Train Communications   WiFi can be used to communicate with moving trains in a metro system. Ordinary WiFi like in my home? Could be.  IEEE802.11g 2.4GHz band, like you use in your home.  But the 5.8-5.9GHz band using 802.11a or 802.11n has certain advantages. There is even an 802.11p available but I think that is reserved for trucking.   http://standards.ieee.org/about/get/802/802.11.html By using WiFi in the 5.8-5.9GHz band you can go to higher power EIRP.  http://en.wikipedia.org/wiki/U-NII  shows this spectrum for 802.11a in the United States.  Most countries, Canada, Europe, Saudi Arabia, etc. will more-or-less follow this spectrum;  perhaps with blocks reserved or different maximum powers. When you want your WiFi access points spread out along the guideway, power determines how close or how far apart your wayside access points can be located.  According to  http://en.wikipedia.org/wiki/U-NII  you can go up to 4Watts=36dBm in the USA. Trains move, fast.  A higher power allows you to space out your Wayside Access points.  100 or 200m being typical.  If the train had to perform a complete logon for every change of access point more time would be spent authenticating than transferring data.  A wireless access controller can reduce time wasted.    http://www.youtube.com/watch?v=0n-uIusTpU8 Finally, everybody has a device that can affect the 2.4GHz range. Laptops, smartphones.  By going to the 5.8-5.9GHz band a cyber-intruder needs to have a wifi device that can work in that "exotic" range. What is in the data? Train position, train speed, commands to stop, commands to go, status and health of train electronics and mechanical equipment, perhaps even who is logged in as driver.  Each manufacturer:  Thales, AnsaldoSTS, Siemens, Bombardier, to name just a few, will have their own proprietary messaging and their own way of doing things for CBTC communications based train control.  But they all have the same goal of moving trains, or stopping trains, without the nuisance of the trains hitting each other. Any WiFi link carrying ATC or CBTC data must be secured.  WPA encryption is only the beginning.  Authentication with passkey and MAC address control are needed, as well.  By writing the CBTC protocol to conform to IEC EN 50159 the actual data messages will be encrypted, again, authenticated and they must make sense to the CBTC servers and clients or they will be rejected.  Any lost messages must be detected and re-transmitted. Just like your home WiFi the SSID beacon can be suppressed.  The train knows what network to connect to and it's not like railway tracks move around a lot.   What else is special about WiFi for Metro Trains Rail alignments are long and skinny. By using a directional antenna you amplify the signal along the track and reduce the waste of power going to the sides. 12-15-18 dBi are common antenna gains. EIRP is the total power put into the antenna, directional gain means the receiver will receive a greater portion of that power. On board the train are many systems using open protocols. To talk to doors, HVAC, break systems you will commonly encounter CANBus, MVB or TWN standards. A voice circuit is needed for a manual operator, a SoftPhone using a VoIP client can connect through the WiFi network along with the ATC, ATS and ATO protocols.   image from researchgate.net

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Nabayan Datta -
Posted 3 months ago

Weight of Indian Railways

Rollingstock

Transport business are based on four basic pillar 'QDDS' of Quantity (Q) to transport, Distance (D) to transport, Duration (D) of transport and sort of Services (S) facilitated by transporter to their customers. In this topic, will discuss about the point Q which is reckoned as the most crucial point for any transportation mode. In India, we have four different mode of transportation to serve the nation inwardly i.e. Surface mode, Railway mode, Airways mode and Inland waterways mode. All of those have their different modal share among transport sector to carry out Passengers and different kind of Goods. In this context, we can definitely says that railway carries the highest tonnage than any other transporter in every financial year. Indian railways carries 1246 kind of goods in 365 type of stocks. Among them Open stocks and Jumbo stocks has highest utilisation index. Every stocks has different kind of characteristics and specifications in terms of weight carrying capacity. Before going to discuss technical & mathematical aspect of it, want to through some light on how quantity are correlated with distance and make GTKM, NTKM like productivity index.    Tonnage Kilometres          At first we should clear the concept of TKM or Tonnage Kilometers index using in railway statistics. What is TKM? TKM is a fundamental unit to express the mobility and loading capacity of a single unit on account of revenue earning work. In other language, how much quantity? For how much distance? lets break the confusion by illustrating this. In 24 hours span, 59 BOXN carried 4179 MT Coal for 300 Kilometers and a 42 BCN carried 2500 MT Food grains for 120 Kilometers. What will be the Gross and Net Kilometres earned by those stocks in 24 hours span? We all have a rooted perception about gross and net is, Inclusiveness means gross and Exclusiveness means net. What are need to exclude to get the net? A locomotive and Some stocks to creates a train. So when we exclude the weight of locomotive and tare weight of wagon, we will get net figure. As per the above mentioned example NTKM of 59 BOXN will be 4179*300=1253700 and of 42 BCN will be 2500*120=300000. This is how distance are correlated with quantity in transportation fields.    Pay to Tare Ratio and Revenue earning We have a transport company, we have some carriers to move out goods. Let, you placed a indent of some goods weighted 50 k.g but our carrier weighted 18 k.g and they can carry only 40 k.g. therefore, the Pay to Tare Ratio of that carrier will be 40k.g/18k.g = 2.2 or 11:5 means if there was 16 total proportion, 11% can be filled with goods against 5% tare load. If the difference between net weight and dead weight are in increasing nature, it meant to be economical growth of the organisation. The low tare load of railway wagons is significant not only to produces the possibility of carrying a higher payload but also increases the energy consumption per payload tonne hauled. One way to reduce the energy consumption per tonne payload is to reduce the tare load. One possibility of lowering the tare load is to reduce the number of components such as a bolster, sideframes, and axles. To take advantage of the lower tare mass, a new concept wagon was conceptualised as a wagon with maximum axle load and with enough load space to ensure a higher tonne gross load. More you can lower dead weight, the more you can carry goods. In IR, currently BOXNS is such a wagon which have the most effective pay to tare ratio with 4.2 or 21:5   Carrying Capacity               Our railway system are in forth position in terms of freight movement. IR loaded 1400+ million tonne of goods in F.Y 21-22 including bulk, break bulk and non-bulk commodities, built light tare wagons, built HHP locos to drag and strengthen their routes to carry effective load. If we notice IR has 4 types of route in terms of carrying capacity. We saw there was a progressive revolution. BG route was started with maximum 22t. Axle load carrying capacity, also called as Excepted CC+6 route then it was extended by 0.4 and made up 22.4t. Axle route also called Universal CC+6 route. Then CC+8 or 22.09t. axle route comes into force. Most of the IR routes are now fitted with 22.09 axle loading capacity but several years ago IR upgraded their 1st 334 k.m long iron ore EXIM route BSPX to PRDP via JKPR into 25t. axle route. After this, almost all iron ore dominating routes of SER, SECR, ECoR and SWR became 25t. axle route. As a result india ranks 4th in iron ore exporting. In this context a question may be arise in mind that despite the highest loaded commodity why coal routes are not universally 25t. axle loading fitted? Probable answer may be given geographically as well as statistically. All soil region of the country are not tough enough as compared to Chottanagpur domain. When a 5800 to 5900t. loaded rake run through 75-80 k.m/hrs it lefts immense impact on soil and track and statistically IR has not enough 25t. axle stock for consequent 25t. coal loading. Thats why at present, 25t. axle loading is permissible only for iron ore in specified routes. Maximum how many tonnage of goods can be loaded in a wagon? This limitation varies on two factor, Carrying Capacity of indented wagon and Carrying Capacity of booked route to reach destination. Wagon CC is a constant index, where Route CC or Permissible Carrying Capacity (PCC) is a variable in accordance with  A. Various route wise  B. Various commodity wise  C. Session wise.  Whenever a consignment booked via more than one type of route i.e Expected CC+6, Universal CC+6, CC+8 and Iron ore route, the permissible weight will be as same as the most restrictive route. Why the commodity factor is discernible in times of wagon loading? IR has sets the commodity wise PCC variety, keeping in mind the significance of agriculture sector, industrial sector, Salt-Sugar like two essential consumable, Food grains and others:-                  1) At the top, Raw materials for plants and Agricultural product had been patronised as Raw materials is a basic factor in making decisions on the establishment of building-material production plants, regardless of the scale of production and Agriculture can be important for developing countries in several ways, where food security is weak it can be a vital source of nutrition, it provides income for farmers and farm workers and thus revenues for rural areas, job opportunities in related areas such as processing and in some cases export revenue.  2) At second, Sugar & Salt commodities that drove the world. For millenia, religion, commerce, war, health, and gold were tied to little white crystals. In the beginning animals wore paths, looking for salt licks, men followed, trails became roads, settlements grew beside them. Scarcity kept salt precious and as civilization spread, two became one of the world’s principal trading commodities.  3) At third, Food grains. Healthy people are assets, they live longer, they should be more productive, and their existence may not be associated with misery and liability. Therefore, national development is incomplete without a healthy population, which accounts for national productivity. That's why healthy food grains that meets food preferences and dietary needs for an active and healthy life.  4) Others commodity except above mentioned commodity head which IR used to carry has the least PCC ever.  IR has also a provision to set PCC session wise. The PCC for carrying coal during monsoon period i.e. 1st July to 15th August when loaded on CC+8 route, shall be 1 tonne less than usual.    Empty Weighment of rakes For instance, in railways weight of loose bulk commodities are determined by deducting the designed tare weight of all wagons (without actually weighing them) from the gross weight of the rake. Railway assume the sum total of designed tare weight of wagons to be the actual tare weight of rake. The designed tare weight of wagons may not be remain same and there is high chance to increase during the course of various overhauling. That is why actual tare weight of rakes should be verify by weighing them in empty condition after a certain periods.   Last word Now a days, overloading by violating PCC beyond tollerance limit is a common scenrrio over IR. Loads are getting originated unweighted under SWA (Sender's Weight Accepted) upto first available motion weighbridge and founded huge overweighted. As per commercial manual V-2 of IR, though there was a provision of collecting overloading charges, but it is not about revenue earnings at all. Railways have permitted the running of trains loaded with enhanced quantity without complying with the conditions laid down for protecting track and rolling stock. Even after permitting loading of wagons with enhanced quantity, the trend of overloading continued. Increased incidence of rail fractures, weld fractures and defects in wagons and locomotives was seen. Such practice should be stopped.      

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Suman Pathak -
Posted 12 months ago

Various Systems of Railway Electrification

Rail Electrification

Various Systems of Railway Electrification Several different types of Railway Traction Electric Power System configurations have been used all over the World. The choice of the system depends on the train service requirements such as  I.    Commuter rail  -Commuter rail typically includes one to two stops per city/town/suburb along a greater rail corridor II.    Freight rail -Rail freight transport is the usage of railroads and trains to transport cargo on land. It can be used for transporting various kinds of goods III.    Light rail -The LRT vehicles usually consist of 2–3 cars operating at an average speed of 55–60 km/h on the lines with more dense stops/stations and 65–70 km/h along the lines with less dense stations IV.    Train load s V.    Electric utility power supply. Railway electrification loads and systems required for light rails, commuter trains, fast high-speed trains, and of course the freight trains are all different. The power demands for these different rail systems are very different. The selection of an appropriate electrification system is therefore very dependent on the Railway system objectives Presently, the following four types of track electrification systems are available: 1. Direct current system—600 V, 750 V, 1500 V, 3000 V  2. Single-phase ac system—15-25 kV, 16 23, 25 and 50 Hz  3. Three-phase ac system—3000-3500 V at 16 2 3 Hz  4. Composite system—involving conversion of single-phase ac into 3-phase ac or dc.   Direct Current Traction System In this traction system, electrical motors are operating on DC supply to produce the necessary movement of the vehicle. Mostly DC series motors are used in this system. For tramways, DC compound motors are used where regenerative braking is required. Regenerative braking   In this type of braking the motor is not disconnected from the supply but remains connected to it and feeds back the braking energy or its kinetic energy to the supply system. The essential condition for this is that the induced emf should be slightly more than the supply voltage.  The various operating voltages of the DC traction system include 600V, 750 V, 1500V, and 3000V. •    DC supply at 600-750V is universally employed for tramways and light metros in urban areas and for many suburban areas. This supply is obtained from a third rail or conductor rail, which involves very large currents. •    DC supply at 1500- 3000 is used for mainline services such as light and heavy metros. This supply is drawn mostly from an overhead line system that involves small currents. Since in the majority of cases, track (or running) rails are used as the return conductor, only one conductor rail is required. Both these supply voltages are fed from substations which are located 3-5 KM for suburban services and 40 to 50KMs for mainline services. These substations receive power (typically, 110/132 KV, 3 phase) from electric power grids. This three-phase high voltage is stepped-down and converted into single-phase low voltage using Scott-connected three phase transformers. This single-phase low voltage is then converted into DC voltage using suitable converters or rectifiers. The DC supply is then applied to the DC motor via a suitable contact system and additional circuitry.   Advantages 1. In the case of heavy trains that require frequent and rapid accelerations, DC traction motors are the better choice as compared to AC motors. 2. DC train consumes less energy compared to AC unit for operating same service conditions. 3. The equipment in the DC traction system is less costly, lighter, and more efficient than the AC traction system. 4. It causes no electrical interference with nearby communication lines. Disadvantages 1. Expensive substations are required at frequent intervals. 2. The overhead wire or third rail must be relatively large and heavy. 3. Voltage goes on decreasing with an increase in length.                 Single-phase ac system In this type of traction system, AC series motors are used to produce the necessary movement of the vehicle. This supply is taken from a single overhead conductor with the running rails. A pantograph collector is used for this purpose. The supply is transferred to the primary of the transformer through an oil circuit breaker. The secondary of the transformer is connected to the motor through switchgear connected to suitable tapping on the secondary winding of the transformer. The switching equipment may be mechanically operated tapping switch or remote-controlled contractor of group switches. The switching connections are arranged in two groups usually connected to the ends of a double choke coil which lies between the collections to adjacent tapping points on the transformer. Thus, the coil acts as a preventive coil to enable tapping change to be made without short-circuiting sections of the transformer winding and without the necessity of opening the main circuit.  Out of various AC systems like 15-25 kV, 16 23, 25, and 50 Hz. Mostly the 25KV voltage is used in railways. The main reason for the 25kV voltage used in the railway is, that 25 kV AC is more economical than a 1.5kV DC voltage system. Since the 25kV voltage system has a higher voltage, the higher voltage reduces the current flow through the conductor; this reflects reducing the conductor size. The cost of the conductor gets less.  However, there are other major advantages for using 25kV voltage system in railway are quick availability and generation of AC that can be easily stepped up or down, easy controlling of AC motors, a smaller number of substations requirement, and the presence of light overhead catenaries that transfer low currents at high voltages, and so on.   Disadvantages 1.  Significant cost of electrification. 2.  Increased maintenance cost of lines. 3.  Upgrading needs additional cost especially in case there are bridges and tunnels. Composite System As the name suggests this system is classified into two types  I single phase to dc system II single phases to 3 phase system Single Phase to DC system The first one single phase to dc system is used where the voltage level is high for transmission and the dc machine is used in the locomotive. This system combines the advantages of high-voltage ac distribution at the industrial frequency with the dc series motors traction. It employs an overhead 25-kV, 50-Hz supply which is stepped down by the transformer installed in the locomotive itself. The low-voltage ac supply is then converted into dc supply by the rectifier which is also carried on the locomotive. This dc supply is finally fed to dc series traction motor fitted between the wheels.                                                                                     Single-phase to 3 phase system Single-phase to 3 phase system is used where 3 phase machine is used in the locomotive and Single-phase track available. In this system, the single-phase 16KV, 50 Hz supply from the sub-station is picked up by the locomotive through the single overhead contact wire. It is then converted into a 3-phase AC supply at the same frequency by means of phase converter equipment carried on the locomotives. This 3-phase supply is then fed to the 3-phase induction motor. References: various EMC Europe IEEE papers, slideshare.net presentations, rail systems, etc.

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Andree Litaay -
Posted 6 months ago

Terminology Go and No Go Test of Switch Machine

Signalling

  TERMINOLOGY GO AND NO GO TEST OF SWITCH MACHINE Go and No Go test or obstruction test always be performed to finalize of point machine installation and point machine maintenance. The purposes of this test to ensure that switch machine on safe condition and ready to use. During train operation or switch machine operation for testing purpose, switch machine failure might be occured. To solve this failure, adjusment on driving rod, detection rod or back drive (if any) are required. Due to those adjustment before switch machine will to use for train operation or testing purposes then Go and No Go test shall be performed. The value of shim to perform this test is depend on the regulation of railway authority in each country or project. For example, in LRT Jabodebek Indonesia Project using 2mm for Go and 4 mm for No Go, PT. KAI (Indoneisa Railway Authority) for subway operation using 3 mm for Go and 5 mm for No Go and KTMB Berhad (Malaysia Railway Authority) at Seremban Gemas Double Track Project and Johor Bahru Sentral Project using 1.5 mm for Go and 2 mm for No Go. To explain about the terminology Go and No Go Test  of switch machine more detail, much better start from analyse the sequences of switch machine operation, refer to a book Railway Signalling  Edited by O.S. Nock , First Published 1980 ©1980 Institution of  Railway  Signal Engineer, on Page 98 with sub-title  “The sequence of operations in power working is therefore” : 1. Unlock the point, by withdrawal of the lock plunger from the srecher bar, nothing that immediatly the lock plunger begins to move the point and lock detection circuit is disconnected. Explanation : Release Locking switch machine and detection. Train operator throw switch machine from LCP or VDU by enforce throw or route set then electric motor will drive the lever to release locking of switch machine and immediatly release locking of detection. It was applied for all of type switch machine. Every switch machine has own type of  driver lever locking (Internal locking and External locking). And the detection also has a two type (Intenal Detection and External Detection). If switch machine cannot perform this step, its could be has a problem with installation. Following below is failure on this step : Electrical Failure     : Fuse was burn out (AC circuit), Bad contact(AC circuit), wiring mismatch, Drop in AC voltage, Motor phase                                      in-balance. Construction failure : Deformation in the switch blades, The levelling of track mismatch, Bad sitting of switch blades to the base                                        plate. Mechanical Failures : Driving rod misalignment, Installation of  back drive too wide (if any).   2. The point are driven across from normal to reverse , or vice versa. Explanation : Switch machine driven  the switch blade through the driving rod from Normal postion to Reverse position  or vice versa until to the new position. On this step the important thing is checking the movement. The movement of switch blade shall be smooth. If any hard movement that indicated has a problem. Following below is failure on this step : Electrical Failure       : Motor phase in-balance, Drop in AC Voltage. Construction Failure : The levelling of track mismatch, Bad sitting of switch blades to the base plate. Mechanical Failure   : Not enough lubrication on the teack element and switch machine.   3. The points are locked in their new position, the last movement of  the locking plunger completing the detection circuit in the new position. Explanation : Switch blade was locked at the new position then the locking detection will re-locked as well. Following below indication of switch machine operation was successful : Switch blade close properly. The opening switch blade has followed the specific value. Switch machine has locking properly. Get position detection. Following below is failure on this step : Electrical Failure       : Fuse was burn out (DC circuit),  Bad contact(DC circuit), wiring mismatch, Drop in DC voltage. Construction Failure : Deformation in the switch blades, The levelling of track mismatch, Bad sitting of switch blades to the base                                        plate, Stock rail misalignment, Fastening bolt or screw on the track element was loose. Mechanical Failure   : Driving rod misalignment, Detection rod misalignment, Fastening bolt or screw on the switch machine                                              element was loose, Installation of strecher bar/back drive (if any) too wide. The main purpose of Go and No Go test is to keep safe condition of turnout while the switch blade at area between switch toe up to driving rod position has a gap. Obstruction Go test for simulate there is has a gap that the trains are allow to passing the turnout. Obstruction No Go test for simulate there is has a gap that the trains are not allow to passing the turnout. Lets analyse parameter of Switches and Wheelset to convincing that Go an No Go test are required. Please see figure 13_Secant contact, refer to document CENELEC DIN EN 13232-9:2012-01 Railway Applications – Track – Switches and Crossing Part 9 : Layout page number  20.   In figure 13 was explained that contact point of stock rail and switch rail shall be not contact with the dangerous zone of  the wheel. To comply this requirement therefore, Go and No Go test are required to be performed for installation and maintenance during train operation. Please see the dangerous zone of the wheel on figure1 – Key wheel dimensions (in addition to profile details), refer to document CENELEC DIN EN 13232-3:2012-01 Railway Applications – Track – Switches and Crossing Part 3 : Requirements for wheel/rail interaction  page number  6.   Obstruction Go test . Purpose of Obstruction Go test to ensure with maximum value the trains are allow to passing the turnout while switch blade get obstacle or deformation which create gap. The test itself using shim with thickness 1.5 mm up to 3 mm (but depend on regulation each country or project). The location of obstacle/shim to carrying the test is from the switch toe up to 20 cm from switch toe. The location shall be there because  the switch toe is the critical zone while the train moving toward set of switch machine. Therefore, with the value of obstruction Go test has  allowed the train passing the turnout. With consideration that contact dangerous zone on wheelset doesn’t has contact with switch blade ( please see figure 14_Safe secant contact, refer to document CENELEC DIN EN 13232-9:2012-01 Railway Applications – Track – Switches and Crossing Part 9 : Layout page number  21). The test procedure itself is put shim with the specific value for Obstruction Go test on the opening switch blade. Throw the switch machine until to the final position. If switch machine was locked and get detection of position, it mean the test is pass.   Obstruction No Go test. Purpose of obstruction No Go test to ensure with minimum value the trains are not allow passing the turnout while switch blade get obstacle or deformation which create  gap. The test itself using shim with thickness 2 mm up to 5 mm (but depend on regulation each country and project). The location of obstacle/shim to carrying the test is from the switch toe up to 20 cm from switch toe. The location shall be there because  the switch toe is the critical zone while the train moving toward set of switch machine. This test will declared pass, while the closed switch blade  has an obstacle No Go  then the end of movement was not in the final position. The meaning if in the final position is refer to a book Railway Signalling  Edited by O.S. Nock , First Published 1980 ©1980 Institution of  Railway  Signal Engineer, on Page 98 with sub-title  “The sequence of operations in power working is therefore”letter (c) The points are locked in their new position, the last movement  of  the locking plunger completing the detection circuit in the new position. Base on the article above, it could be concluded that the final position of switch machine movement is switch blade was locked in the new position and then the detection circuit get in the new position. Therefore, while closed switch blade has an Obstruction No Go then it will be not locked and no detection. The main purpose this test is to avoid derailment while the gap of closed switch blade too big. Therefore, with obstruction No Go test could  identify that turnout unsafe condition. Because the position of closed switch blade doesn’t in the final position. To make a clear why if the closed switch blade is unsafe condition please see figure 15_Dangerous secant contact, refer to document CENELEC DIN EN 13232-9:2012-01, Railway Applications – Track – Switches and Crossing Part 9 : Layout page number  22 . In figure 15 explained that if the gap too wide, the contact dangerous zone of wheelset will contact with switch blade. With this condition has possibility the wheelset will climbed out the switch blade. But the value of obstruction No Go has been confirmed by manufacture that the value still on minimum risk. The author's purpose in this article is to deep search about the topic above. If the readers has another reference regarding the topic or any critics or any suggestion please feel free to comment to this article. Because this opening discussion for everyone. ======================================================================================================= Author : Andree Litaay Reference : CENELEC DIN EN 13232-9:2012-01, Railway Applications – Track – Switches and Crossing Part 9 : Layout CENELEC DIN EN 13232-3:2012-01 Railway Applications – Track – Switches and Crossing Part 3 : Requirements for wheel/rail interaction Railway Signaling Edited by O.S. Nock , First Published 1980 ©1980 Institution of  Railway  Signal Engineer

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Deepu Dharmarajan -
Posted 2 years ago

SRA (TfNSW) SIGNALLING & ELECTRICAL SYMBOLS

Signalling

CONTENTS   The following pages show the signalling and schematic symbols used by the State Rail Authority of New South Wales on their plans and drawings. They are provided for reference use throughout the course. They are reproduced from SRA (Currently TfNSW) training material.   TRACK PLAN AND WORKING SKETCH SYMBOLS MECHANICAL SIGNALS POWER WORKED SIGNALS SINGLE LIGHT INDICATION WAYSIDE BUILDING AND STRUCTURES TRACK CIRCUIT DEVICES INTERLOCKING SYMBOLS APPARATUS HOUSINGS RELAYS AND CONTACTS CONTACTS OPERATED BY SIGNALS LOWER QUADRANT SEMAPHORE SIGNALS, INCLUDING BANNER SIGNALS CONTACTS OPERATED BY POINTS LEVER CONTACTS CATCH ROD CONTACTS MISCELLANEOUS APPARATUS 

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Josef Winter -
Posted 12 months ago

Solar-powered video surveillance for tracks

Safety and RAMS

The solar video surveillance system was specially developed for an application without power supply and network connection for railroad use. This system is the ideal and cost-effective solution for video surveillance, at locations without existing infrastructure. The RAILWAY CONTROLLING models can be used in all locations where sunlight and mobile phone reception are available. All models meet strict security requirements.   Ideally suited for: - Track surveillance - Tunnel portal surveillance - Storage yard surveillance - Weather monitoring   Visit: http://railway-controlling.com/index.html  

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Pravin_pasare -
Posted one year ago

Slab track VS Ballasted Track

Rail Tracks

No. DESCRIPTION BALLASTED TRACK BALLASTLESS TRACK 1.       Maintenance Input. Frequent maintenance & non-uniform degradation Less maintenance for geometry. 2.       Cost comparison Relatively low construction costs but higher life cycle cost. Relatively high construction cost but lower life cycle cost. 3.       Elasticity. High elasticity due to ballast. Elasticity is achieved through use of rubber pads and other artificial materials. 4.       Riding Comfort. Good riding comfort at speeds up to 250 – 280 kmph. Excellent riding comfort even at speeds greater than 250 kmph.   5.       Life expectation (20 yrs) (50-yrs) 6.       Stability. Over time, the track tends to “float”, in both longitudinal and lateral directions, as a result of Non-linear, irreversible behaviour of the materials. No such problem. 7.       Lateral resistance Limited  compensated Lateral acceleration in curves, due to the limited lateral resistance offered by the ballast. High lateral resistance to the track which allows future increase in speeds in combination with tilting coach technology. 8.       Noise. Relatively High noise Relatively low noise and vibration nuisance. 9.       Churning up of Ballast. Ballast can be churned up at high speeds, causing serious damage to rails and wheels. No such damage to rails and wheels. 10.  Construction cost of Bridges/Tunnels/ etc. Ballast is relatively heavy, leading to an increase in the costs of building bridges and viaducts if they are to carry a continuous ballasted track. Less cost of construction of bridges and viaducts due to lower dead weight of the ballast-less track. 11.   Construction Depth. Depth of Ballasted track is relatively high, and this has direct consequences for tunnel diameters and for access points. Reduced height.

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TOJO THOMAS -
Posted 10 months ago

Signalling Installation Design - Part 1

Signalling

In general, least importance are given to Installation Design compared to System Design ! This is mainly due to lack of awareness and knowledge  among  the key personals within an organisation. An error in a system application software or any design engineering document can be rectified by spending few hours and the cost impact is minimal compared to an error in an Installation Design. As a person who worked in both aspect of these two designs, I felt that we should emphasize more on Installation Design. A minor error in a mechanical cable frame, cable junction box, fixing brackets or a signal mast design will have a huge impact on material wastage, impact of schedule and budget in a larger way. There are various things to be considered to produce an error free design, which I describe based on design and site experience I received in the projects I have executed. I have tried to explain in this article the flow of work that happens in Installation design engineering from the Tender to the execution of installation activities at site. I have divided the work done by installation engineer into the following section. It is defined as per the schedule/flow of activities. TENDER: Firstly, before starting any Installation engineering activities we do have a tender phase. In this phase we analyse basically 2 main information which is important for the project management team to decide the cost. Ultimately everything comes down to the cost, each system has forecasted!!! The 2 main information required during the tender phase is the number of hours we will spend and the number of items we will be procuring. This information is collected in the format of BOQ (Bill of quantity and workload file. So, in this section I will explain what should not be missed (inputs and outputs) during the tender phase: Inputs/Reference documents Requirement matrix: This document has the information from the customer required for each system. Installation engineering team has to extract the installation requirements with respect to each other engineering sub system. This drawing also will have the standards(EN, IS, ASTM, IEC, etc) that should be followed in the respective country. Civil Architecture drawings/CSD(Combined Services drawing): These are a set of drawing which will give an outline of the building and the location of the equipment room in the station or control centre. This will also have the general information on the cable routing inside the building. This drawing will help us to calculate the cable length that has to be considered for each run of the cable. Cross Section drawing of the track: This will give a general information on the type of accessories and mounting support we need to consider for each equipment defined in the scheme plan. This will also provide the information on the cable ducts that can be used for SIG and COM. With this drawing, we also get to know what strategy that can be applied to cross the cables between the tracks. Track Alignment drawing: This drawing will give us the gradient of the tracks and the vertical/horizontal alignment of both the up & down track. This drawing along with scheme plan will help us to calculate the cable length along the track along. Also, this drawing will help us to analyse if the track is elevated, on ground and underground which will in turn help the team to analyse the mounting arrangement for trackside equipment. Scheme plan: This is the deliverable from engineering team that defines the kilometric point of each equipment and the number of trackside equipment. It is used to calculate the cable length and quantify the number of mounting arrangements that needs to be considered against each signalling and telecom equipment along the track. System BOQ: This document will have the information on the quantity of the equipment that will be installed along the trackside and in the stations. We can decide on quantity of the support required for each different equipment. Cable layout: This drawing gives a general information on the cabling schematics between the cubicle in the equipment room and trackside equipment. We use this deliverable to define the type of cables and the length required for each type of equipment. Interface management: This is plan created along with the customer on who will give what information. This also states what are the supports other subsystem require from installation team. Planning schedule: This will provide a general information on the schedule of each activity during the execution of project. This will in turn help the team to forecast the installation engineering activities. Output/ Installation Deliverables Installation BOQ: After analysing the inputs from the customer and other engineering team within the project team (inputs are listed above), Installation team will prepare the installation BOQ. This document contains all the items related to installation such as cable trays and it accessories, mounting support and its accessories, cables, material needed for cable crossing the track, cable tags, tags, racks, base frames, conduits, trackside junction box and its accessories, clamps, cable glands, grounding mechanism, etc. Installation workload file: This document consists of the number of deliverables that needs to be considered along with the hours dedicated to each deliverable. This document will also include the information on the scope of work for installation design team with respect to the site activities (Whether shared or full-time resources is dedicated for each activity). We also include the information on the assumptions taken during the workload calculation. According to the planning of the schedule for each activity we forecast the hours.   For Preliminary installation Design to Detailed Installation Design do follow the page for more....

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Somnath Pal -
Posted 12 months ago

RAMS of a Vital Input Card

Safety and RAMS

CHAPTER -1  Introduction For a Railway Signal Interlocking system, Field Input conditions to be monitored by the Interlocking equipment are Track Cct / Axle Counter, Point Detection, Signal Aspect Proving, Level Crossing Gate, Crank Handle and Panel Buttons. The monitoring is done by reading the Pick-up or Drop contacts of corresponding Relays. This could have been done by operating a Transistor through external Voltage fed via the pick-up Contact of the Relay. The Output of Transistor is processed by the Logic Solver ( Processor). But in that case, there would be no Isolation between external Analog Input and internal Digital Output circuits. An Opto Coupler is used for this purpose, where the Input LED and Output Phototransistor are electrically isolated . The Input through Pick-up contact of Relay operates the LED of the Opto Coupler, light from which turns the output Phototransistor. The  interfacing using a Transistor and an Opto coupler is showed in Fig 1(a)&(b) When the Relay is in Pick-up condition, the Transistor is Forward biased and Collector Output to Processor is ‘0’ . During Drop condition of the Relay, Collector Output is ‘1’ . Input Interface Card converts the Analog information of DC Voltage fed through the Relay contacts to send TTL level to Processor. The basic features of the Card are: All Inputs are fed through Opto Couplers having a minimum Isolation Voltage of 1500V.   All Inputs are protected from Transient Voltages and Surges by using Varistors. To reduce Single-point Failure, both Front and Back potential-free contacts of each external Relay are interfaced. They are read through different Ports and Bits to avoid common-mode failure. Each Card gets Hardware Address of the particular Slot of the Backplane, to which it is inserted. This Address must be matched with the Software Address sent by Logic Solver Card before the external Relay Inputs are read. Input Cards can be inserted or extracted with System Power-ON conditions. A special circuit is used to prevent transient to Stable +5V Supply to ICs, Input data are read employing Input Toggle by the logic Solver or using multiple sets of Opto Couplers ensuring Hardware redundancy. The Input Data Structure of the Interlocking System Inputs is given in Fig 2: Panel Buttons and Keys are called Non-Vital Inputs and a Non-Vital Input / Output Card is used to read 32 Inputs . All other Inputs are Vital Inputs and a Vital Input Card reads 16 Relay Inputs.   A detailed diagram is showed in Fig 3 . Since Railway Interlocking is a Safety-critical System, Inputs from both Pick-up and Drop Contacts of a Relay is analysed. Each Input is monitored by Opto Couplers by supplying Current from an Isolated 12V Supply . The Input to Processor will be ‘ 01’ in Drop Condition and ‘ 10’ in Pick up Condition . These two combinations are Valid Inputs . Other two Inputs ‘ 00’ and ‘ 11’ are Invalid and Processor will show Fault. But during transition of Relay between Drop to Pick-up or Pick- up to Drop , both the Opto Couplers will be OFF . So, Output will be ‘11’ , which is Invalid A De-bouncing circuit (U1) is used for feeding steady Input to the Logic Solver. In this case, during transition of Relay, the Input to Processor will remain unchanged from Last State. When the Relay X is not operated , current flows through the Drop Contact , Inductor, L1, Current Limiter R1, Resistor R2 and input Diode of Opto Coupler OC1. The Opto Coupler conducts and a level ‘ 0 ’ is fed to Pin1 of U1 . This makes output Pin 3 of U1  as ‘ 1 ’. At the same time, since no current passes through Input Diode of OC2, it does not  conduct. Level ‘1’ is fed to  Pin 5 of U1 and output   Pin 6 of U1 to Port becomes ‘0’. Thus we get a pattern 0101 at the Port. When the Relay X is operated , current flows through the Pick-up Contact ,  Inductor L2,  Current Limiter R5, Resistor R6 and input Diode of Opto Coupler OC2. The Opto coupler conducts and a level ‘0 ’ is fed to Pin 5 of U1 . This makes output to Pin 6 of U1   as ‘0’ . At the same time, since no current passes through Input Diode of OC1, it does not  conduct. Level ‘1’ is fed to  Pin 1 of U1 and output to Pin 3 of U1 to Port becomes ‘0’ .This time, the inputs to Port changes to 1010 . We find that Port inputs 0101 and 1010 are the valid levels . All other combinations  are invalid levels. If Hardware De-bounce Cct U1 is replaced by Software De-bounce to reduce Parts Count to enhance Reliability, the inputs to Port will change to 01 when Relay X is not operated and 10 when it is  operated. If a vital decision is taken by   Pick-up condition of Relay X, then a failure to read Pick-up condition as Drop, is a Safe failure . But if Drop condition is read as Pick-up condition, it will be Unsafe failure . Now we shall have to do an Failure Mode Effects & Criticality Analysis (FMECA)  study of the Cct showed in Fig 3 and identify the critical component to cause Unsafe Failure and mitigate the Hazard. Failure Mode Effects & Criticality Analysis (FMECA) We shall first study the failure modes of the components. For every failure mode of components , we shall their effect for Drop and Pick-up conditions. Typical faults of an Electronic component are Open Cct, Short Cct, Drift in Parameter and Functional Faults. Average relative frequencies of Failure Modes of various Components are given in the Table 1 below. Terminating Resistors and Current Limiting Resistors are of mainly Metal Film type for which Short cct Mode is incredible and hence are not considered. When Resistors are used in Nodes with Pull up Totem-pole Driver , even Drift in value is not to  be considered. For open Collector Modes like Opto coupler output, the design ensures much higher Collector current as well as Diode input current , so that even  ± 20% Drift does not affect the Circuit behaviour. So, for Resistors , only Open Cct Mode is considered. For Inductors, any Drift will not affect normal operation and only Open Mode of failure is considered. For Varistor, Open Mode does not affect normal operation and if the Clamp Voltage is chosen much higher than the required Value , Drift also does not have any effect. Only Short cct Mode is analysed . For ICs, both s-a-0 and s-a-1 Faults are considered for every Pin. Now we will consider component-wise FMECA. The effects during Relay Drop  and Pick-up conditions are analysed for each Component Failure. a) If Inductor L1 is Open Relay Drop condition: Current does not pass through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  aIso ‘1’. Output  to Port will be ’1011’. Fault is detected as Invalid Data and failure is Safe.  Since both the Inputs to Debounce Cct are at ‘1’, its Output will remain at last State, i.e. 01. Relay Pick-up condition : Current  passes through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘0’. Output  to Port will be ’1010’. Fault is not detected  and failure is Safe.  b) If Inductor L2 is Open Relay Drop condition: Current does not pass through input of Opto Coupler OC2. U1 pin5  is at ‘1’ and U1 pin 1 is at ‘0’. Output  to Port will be ’0101’. Fault is not detected and failure is Safe.  Relay Pick-up condition : Current  passes through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  also at ‘1’. Output  to Port will be ’1011’. Fault is  detected  as invalid data. c) if Metal Oxide Varistor RV1 is Short : Relay Drop condition: Current does not pass through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  aIso ‘1’. Output  to Port will be ’1101’. Fault is detected as invalid data and failure is Safe.  Relay Pick-up condition : Current  passes through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘0’. Output  to Port will be ’1010’. Fault is not detected  and failure is Safe.  d) if Metal Oxide Varistor RV2 is Short : Relay Drop condition: Current does not pass through input of Opto Coupler OC2. U1 pin5  is at ‘1’ and U1 pin 1 is at ‘0’. Output  to Port will be ’0101’. Fault is not detected and failure is Safe.  Relay Pick-up condition : Current does not pass through input of Opto Coupler OC2. U1 pin 5 is at ‘1’ and U1 pin 1 is  aIso ‘1’. Output  to Port will be ’1011’. Fault is detected as invalid data and failure is Safe.  e) If Current Limiting Resistance R1 is Open: Relay Drop condition: Current does not pass through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  aIso ‘1’. Output  to Port will be ’1101’. Fault is detected as invalid data and failure is Safe.  Relay Pick-up condition : Current  passes through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘0’. Output  to Port will be ’1010’. Fault is not detected  and failure is Safe.  f) If Current Limiting Resistance R2 is Open: Relay Drop condition: Current does not pass through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  aIso ‘1’. Output  to Port will be ’1101’. Fault is not detected data and failure is Safe.  Relay Pick-up condition : Current  does not pass through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is also at ‘1’. Output  to Port will be ’1011’. Fault is  detected  as invalid and failure is Safe.  g) If Current Limiting Resistance R5 is Open: Relay Drop condition: Current does not pass through input of Opto Coupler OC2. U1 pin 1 is at ‘0’ and U1 pin 5 is  aI ‘1’. Output  to Port will be ’0101’. Fault is not detected data and failure is Safe.  Relay Pick-up condition : Current  does not pass through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘1’. Output  to Port will be ’1010’. Fault is not detected  and failure is Safe.  h) If Current Limiting Resistance R6 is Open: Relay Drop condition: Current does not pass through input of Opto Coupler OC2. U1 pin 1 is at ‘0’ and U1 pin 5 is  aI ‘1’. Output  to Port will be ’0101’. Fault is not detected data and failure is Safe.  Relay Pick-up condition : Current  does not pass through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘1’. Output  to Port will be ’1010’. Fault is not detected  and failure is Safe.  i) If Protection Diode D1 is open: Normal operation of the cct is not affected. But a reverse voltage of more than 6V during Drop condition would damage the Diode of Opto coupler OC1. During Pick-up condition, there is no effect. j) If Protection Diode D2 is open: Normal operation of the cct is not affected. But a reverse voltage of more than 6V would damage the Diode of Opto Coupler OC2 during Pick-up. There is no effect during  Drop condition. k) If Protection Diode D1 is short: Relay Drop condition: Opto coupler OC1 will be OFF since current will  be bypassed via D1. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘1’. Output  to Port will be ’1101’. Fault is detected as invalid data and failure is Safe.  Relay Pick-up condition : Opto coupler OC1 will be OFF since current will  be bypassed via D1. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘1’. Output  to Port will be ’1010’. Fault is not detected failure is Safe.  l) If Protection Diode D2 is short: Relay Drop condition: Opto coupler OC2 will be OFF since current will  be bypassed via D2. U1 pin 1 is at ‘1’ and U1 pin 5 is  also at ‘1’. Output  to Port will be ’ 0101’. Fault is not detected and failure is Safe.  Relay Pick-up condition : Opto coupler OC2 will be OFF since current will  be bypassed via D2. U1 pin 1 is at ‘1’ and U1 pin 5 is  aIso ‘1’. Output  to Port will be ’1011’. Fault is detected as invalid data and failure is Safe. m) If Input Diode of Opto Coupler OC1 is open: Relay Drop condition: Current does not pass through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  aIso ‘1’. Output  to Port will be ’1101’. Fault is detected as invalid data and failure is Safe.  Relay Pick-up condition : Current does not pass through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  at ‘0’. Output  to Port will be ’1010’. Fault is not detected  and failure is Safe.  n) If Input Diode of Opto Coupler OC2 is open: Relay Drop condition: Current does not pass through input of Opto Coupler OC2. U1 pin 5  is at ‘1’ and U1 pin 1 is at ‘0’. Output  to Port will be ’0101’. Fault is not detected and failure is Safe.  Relay Pick-up condition : Current  does not pass through input of Opto Coupler OC2. U1 pin 1 is at ‘1’ and U1 pin 5 is  also at ‘1’. Output  to Port will be ’1011’. Fault is  detected  as invalid data. o) If Collector in Opto Coupler OC1 is open: Relay Drop condition: Due to the pull up Resistor 5, Current does not pass through input of Opto Coupler OC1. U1 pin 5  is at ‘1’ and U1 pin 1 is at ‘0’. Output  to Port will be ’0101’. Fault is not detected and failure is Safe.  Relay Pick-up condition : Opto Coupler OC2 starts conducting  and port input becomes 0101. Fault is not detected  and failure is Safe.  p) If Collector in Opto Coupler OC2 is open: Relay Drop condition: Current does not pass through input of Opto Coupler OC2. U1 pin5  is at ‘1’ and U1 pin 1 is at ‘0’. Output  to Port will be ’0101’. Fault is not detected and failure is Safe.  Relay Pick-up condition : Current  passes through input of Opto Coupler OC1. U1 pin 1 is at ‘1’ and U1 pin 5 is  also at ‘1’. Output  to Port will be ’1011’. Fault is  detected  as invalid data. q) If Collector and Emitter of OC1 is short: Relay Drop condition: We get  1 in Pin 1 of U1 and port gets data 0101. Fault is not detected and failure is Safe.  Relay Pick-up condition : Both pins 1 and 5 get 1 and we get 0110. Fault is  detected  as invalid data. r) If Collector and Emitter of OC 2 is short: Relay Drop condition: We get  1 in Pin 5 of U1 and port gets data 1010. Fault is not detected and failure is Safe.  Relay Pick-up condition : Both pins 1 and 5 get 1 and we get 0110. Fault is  detected  as invalid data. s) If Pull up Resistor R3 is open: Relay Drop condition: Since Opto Coupler OC1 is in operated condition, we get  0 in Pin1 of U1 and port gets data 0101. Fault is not detected and failure is Safe.  Relay Pick-up condition : If there is large leakage current from Supply and Ground, the Collector of Opto coupler OC1 will be at level ‘0’. So data to  port will be 0110. Fault is  detected  as invalid data. t) If Pull up Resistor R7 is open: Relay Drop condition: Since Opto Coupler OC2 is in operated condition, we get  0 in Pin5 of U1 and port gets data 0110. Fault is detected as invalid data and failure is Safe.  Relay Pick-up condition : If there is large leakage current from Supply and Ground, the Collector of Opto coupler OC1 will be at level ‘0’. So data to  port will be 1010. Fault is  not detected.  u) If S-a-0 fault is at Pin 1 of U1: Relay Drop condition: Pin 3 of U1 will be ‘1’ and Port Input is 0101. Fault is not detected. Relay Pick-up condition : Port Input will be 0110, which is invalid. v) If S-a-0 fault is at Pin 5 of U1: Relay Drop condition: Pin 6 of U1 will be ‘1’ and Port Input is 0110 which is invalid. Relay Pick-up condition : :Port Input will be 1010. Fault is not detected. w) If S-a-1 fault is at Pin 1 of U1: Relay Drop condition: Pin 1 and Pin 5 of U1 both will be ‘1’ and Port Input remains 0101. Fault is not detected. Relay Pick-up condition : Port Input will be 1010. Fault is not detected. x) If S-a-1 fault is at U1-5: Relay Drop condition: Pin 6 of U1 will be ‘0’ and Port Input is 0101.  Fault is not detected. Relay Pick-up condition : Pin 1 and Pin 5 of U1 both will be ‘1’ and Port Input remains 1010. Fault is not detected. y) If S-a-0 fault is at U1-3: Relay Drop condition: Pin 3 of U1 will be ‘0’ and Port Input is 0011, which is invalid. Relay Pick-up condition : Port Input is 1010. Fault is not detected. z) If S-a-0 fault is at U1-6: Relay Drop condition: Port Input is 0101. Fault is not detected. Relay Pick-up condition : Port Input is 1100, which is invalid. aa) If S-a-1 fault is at U1-3: Relay Drop condition: Port Input is 0101. Fault is not detected. Relay Pick-up condition : Port Input is 1101, which is invalid. ab) If S-a-1 fault is at U1-6: Relay Drop condition: Port Input is 0111, which is invalid. Relay Pick-up condition : Port Input is 1010. Fault is not detected. ac) If R4 is Open: Relay Drop condition: LED 1 will not glow. Since LED 2 also does not glow, fault can be usually detected. Relay Pick-up condition : Since LED 2 glows, fault cannot be detected. ad) If R8 is Open: Relay Drop condition: Since LED 1 glows, fault cannot be detected. Relay Pick-up condition : LED 2 will not glow. Since LED 1 also does not glow, fault can be usually detected . ae) If LED1 is faulty: Relay Drop condition: LED 1 will not glow. Since LED 2 also does not glow, fault can be usually detected. Relay Pick-up condition : Since LED 2 glows, fault cannot be detected. af) If LED2 is faulty: Relay Drop condition: Since LED 1 glows, fault cannot be detected. Relay Pick-up condition : LED 2 will not glow. Since LED 1 also does not glow, fault can be usually detected. In summary, Invalid Input is obtained in Relay Drop condition if OC1 Output is Short OC2 Input or Output is Open U1-3 S-a-1 U1-6 S-a-0 Similarly, Invalid Input is obtained in Relay Pick-up   condition if OC1 Input or Output is Open OC2 Output is Short U1-3 S-a-0 U1-6 S-a-1 It also shows that a single fault cannot lead to Unsafe Failure. After the completion of FMECA, we are to perform Fault Tree Analysis (FTA) of the Circuit to identify the causes of Safe and Unsafe Failures .                                                        Fault Tree Analysis (FTA) We shall now learn how the Circuit can fail to operate. So, we shall make a Fault Tree Analysis as shown below. Fault trees are individually made for both Safe as well as Unsafe Failures. Safe Failure can occur due to Two simultaneous Faults --- Open Cct Fault in Opto Coupler OC2 as well as Short Cct Fault in Opto Coupler OC1. Unsafe Failure can occur due to Two simultaneous Faults --- Open Cct Fault in Opto Coupler OC1 as well as Short Cct Fault in Opto Coupler OC2.     Unsafe Failure can happen only due to simultaneous Faults in Open cct in Relay NO path and Short cct in Relay NC path.         CCT UNSAFE FAILURE (0101 is read as 1010)               Once we prepare the Fault Tree, we are to calculate the Failure Rate of the Card .               For this, we are initially to find the Basic Failure Rate for each component as per Calculations given in MIL Std 217F . Then we are to Calculate the actual Failure Rate under environmental stress.   The environmental stress factors are : λ C =  Contact Constitution Factor λ Q = Quality Factor λ E =  Environmental Factor. We consider Ground Fixed λ T =  Temperature Factor λ s =  Electrical Stress Factor λ R =  Resistor Value factor λ CV = Capacitor Value Factor   Typical Calculations for a Components are showed in Chapter. The following Table shows the individual Component Failure Rates for the Input Interface Cct. We have seen that Unsafe Failure can be caused only by 2 simultaneous failures – Open Circuit in OC 1 and Short Circuit of OC 2 Output. So, the Failure Rate will be the Product of Individual Failure Rates of the 2 Opto Couplers. From the table above, we find that the Failure Rate of an Opto Coupler is 0.0257 X 10 -6 . So, the Unsafe Failure Rate will be ( 0.0257 X 10 -6 ) 2 = 6.6040 X 10 -16.  This is far above the requirement of SIL 4. Total Failure Rate of the Card is 3.375477 X 10 -6 giving a Mean Time Between Failure of 296254.4 Hours. Reliability after a period of One year (8760 Hrs) i s R = e – λt     = e - 0.0000033754 X 8760    = e – 0.029568    = 0.97086   Designed Life with 99% Reliability = (- ln 0.99) / 0.0000033754 = 0.01005033585 / 0.0000033754 = 2977.5 Hrs. Preventing Common- Mode Failures: To reduce Common- mode failures, we can feed U1 outputs in two different Ports and that too at different Input Pins . For example, if Pin 3 of U1 is fed to D0 of Port A, Pin 6 of U1 should be fed to D7 of Port B . Then we can match them through Software in Processor Card. See the Diagram of the connection in Fig 4 A Program for the same task is written below in 8085 Assembly language. START:          IN Port 1                     :   Read Drop Contact Data                        MOV D, A                  :    Save Data                        IN Port 2                     :    Read Pick-Up Contact Data MATCH:         PUSH D                     :    Save Drop Contact Data                        CMA                           :    Invert Pick-Up Contact Data                        MOV B, A                  :   Save Data                        MVI C, 00                  :   Initialize Register ‘C’                        LXI H, 0180                :   Initialize Registers : ‘H’ and ‘L’                        MVI E, 08                  :    Load Count (8) for the Loop Iterator LOOP  :         ANA H                        :    Mask Unconcerned Bits of the Pick-Up* Data                        JNZ ONE                    :    If Data Bit is Not 0, Go to Label ONE                         MOV A, L                   :    Transfer Data from Register ‘L’ to ‘A’.                         CMA                           :    Invert Data of Accumulator                         ANA C                        :    Mask Unconcerned Bits                         JMP ZERO                 :    Go To Label ZERO . ONE    :          MOV A, C                  :    Copy Contents of ‘C’ to Accumulator                       ORA L                        :    Make MSB ‘1’ and progress with other bits ZERO  :          MOV C, A                  :    Save the new value in Register C                      MOV A, H                  :    Load Bit Position Indicator in Accumulator                      ADD H                       :    Shift Left for Next Bit indicator                        MOV H, A                  :   Save the Bit Indicator Data.                                     MOV A, L                   :   Load Bit Position in Accumulator                            RRC                           ;    Go to Next Bit Position                        MOV L, A                :    Save Updated Bit Position Data                        MOV A, B                :    Read saved Pick-up* Contacts Data                        DCR E                    :    Check for completion of all 8 Bits           JNZ LOOP             :  Repeat Rearranging for all 8 Bits                         MOV A, C              :  Save Rearranged Pick-up* Data                         POP D                   :  Restore Saved Drop Contact Data                        RET                       :  Go back to Main Programme                        CMP D                   :   Compare Drop and Pick-up* Data                       JNZ FLT                 :   If not Matched, Go to Fault This Subroutine is Executed in 34.5 μs, considering that each State in 8085 generally takes 330 ns for execution .   Toggling of Input data to detect Opto Coupler Faults Instead of keeping the Emitter of Opto Coupler permanently Grounded, we feed ‘0’ from Processor through Port C of Programmable Peripheral Interface 8255, to the Emitters as showed in Fig 5.   After reading the input and analysing, we momentarily feed ‘1’ to the Emitters. Now, all the opto-couplers should be OFF. That means, Opto-coupler outputs should follow the Toggling input from the microprocessor. Now, we again feed ‘0’ from the Processor and analyse the Opto-coupler Outputs finally. We take inputs from Drop Contacts of 4 different relays along with the Output of U1 Pin 3 of their De-bounce circuits, via Port ‘A’ of 8255. Similarly, the pick-up Contacts of the same four Relays and Output from U1 Pin 6 are taken through Port ‘B’. For 16 relays, Interface to the Card, 4 numbers of 8255 ICs PPI 8255   1 are needed. The Programme for the Toggle Operation is given below:   MVI A, 92                 Programme Four PPIs (8255) having     OUT 03                           PORT A -- INPUT OUT 07                           PORT B -- INPUT OUT 0B                          PORT C -- OUTPUT OUT 0F                           LXI H, 1100               Starting Location to keep Drop Contacts Data SUB A                       Enable Opto Couplers in PPI 1 OUT 02 IN 00                         Read Drop contact Status from PPI 1 MOV M, A                 Save in Location 1100 IN 01                         Read Pick-up contact Status from PPI 1 CALL MATCH          Rearrange Bits and Match them. INX H                        Go to Next Location SUB A                       Enable Opto Couplers in PPI 2 OUT 06 IN 04                        Read Drop contact Status from PPI 2 MOV M, A                Save in Location 1101 IN 05                        Read Pick-up contact Status from PPI 2 CALL MATCH         Rearrange Bits and Match them. INX H                       Go to Next Location SUB A                      Enable Opto Couplers in PPI 3 OUT 0A IN 08                        Read Drop contact Status from PPI 3 MOV M, A                Save in Location 1102 IN 09                        Read Pick-up contact Status from PPI 3 CALL MATCH         Rearrange Bits and Match them. INX H                       Go to Next Location SUB A                      Enable Opto Couplers in PPI 4 OUT 0E IN 0C                        Read Drop contact Status from PPI 4 MOV M, A                Save in Location 1100 IN 0D                        Read Pick-up contact Status from PPI 4 CALL MATCH         Rearrange Bits and Match them.                            STA 1100                Bring Drop Contact Data from Location 1100 LXI H , 1200             Initialize Flag Location for First Relay of PPI 1 IN 00                       Read Drop contact Status from PPI 1        CPI 55                      Check if this Data is same as the Saved Data JZ PPI 2 CALL DELAY 1ms  Wait for 1 milli second MVI A, FF                 Disable Opto Couplers OUT 02 IN 00 CALL DELAY 1ms  Wait for 1 milli second CPI FF JNZ FLT                   If not, Go to Fault SUB A                      Again Enable Opto Couplers OUT 02 IN 00 CPI 55 CNZ PROCESS PPI 2    :             STA 1101                   Bring Drop Contact Data from Location 1101 LXI H , 1204                 Initialize Flag Location for First Relay of PPI 2 IN 04                           Read Drop contact Status from PPI 2 CPI AA JZ PPI 3 CALL DELAY 1ms     Wait for 1 milli second MVI A, FF                    Disable Opto Couplers OUT 06 IN 04                            Read Drop contact Status from PPI 2 CALL DELAY 1ms     Wait for 1 milli second CPI FF                        Check if Opto Couplers are Disabled JNZ FLT                      If not, Go to Fault SUB A                        Again Enable Opto Couplers OUT 06 IN 04                           Read Drop contact Status from PPI 2 CPI AA CNZ PROCESS PPI 3       :        STA 1102                   Bring Drop Contact Data from Location 1102 LXI H , 1208                Initialize Flag Location for First Relay of PPI 3 IN 08                          Read Drop contact Status from PPI 3 CPI 55                   JZ PPI 4 CALL DELAY 1ms   Wait for 1 milli second MVI A, FF OUT 0A IN 08                         Read Drop contact Status from PPI 3 CALL DELAY 1ms   Wait for 1 milli second CPI FF                      Check if Opto Couplers are Disabled JNZ FLT                   If not, Go to Fault SUB A                       Again Enable Opto Couplers OUT 0A IN 08                        Read Drop contact Status from PPI 2 CPI 55 CNZ PROCESS PPI 4    :             STA 1103                 Bring Drop Contact Data from Location 1104 LXI H , 120C              Initialize Flag Location for First Relay of PPI 4 IN 0C                        Read Drop contact Status from PPI 4 CPI AA   JZ NXT_CARD CALL DELAY 1ms  Wait for 1 milli second MVI A, FF                 Disable Opto Couplers OUT 0E IN 0C                         Read Drop contact Status from PPI 4 CALL DELAY 1ms  Wait for 1 milli second CPI FF                       Check if Opto Couplers are Disabled JNZ FLT                   If not, Go to Fault SUB A                       Again Enable Opto Couplers OUT 0E IN 0C                         Read Drop contact Status from PPI 4 CPI AA CNZ PROCESS   PROCESS   :    MOV B, A     MVI C, 04                MVI D, 40                              CHK             :     MOV B, A               ANA D               JNZ PICK-UP               MVI A, FF               MOV M, A PICK-UP       :  MOV A, D RLC MOV D, A ANA D JNZ FLT SUB A MOV  M, A INX H MOV A, D RLC MOV D, A DCR C JNZ CHK   dELAY 1 ms :   PUSH D BACK           :    LXI B , 0BB1                            DCX B JNZ BACK POP D RET  This Programme to check the Status of the Relays Interfaced in One Card takes about 9.64 ms . Thus to check all 16 Input Cards, a total time of 154 ms is needed. It covers up the Transition periods for QN1 Relays. Card AcCcess Whenever an Input Card is inserted into one of the I/O Slots, it gets the I/O Slot address , which is Hardwired in Back-plane . Processor Card sends Motherboard Slot addres s through the I/O Bus. When the two addresses match, the Comparator Output Pin gets low and a Decoder and Data Buffer are enabled. The arrangement is showed in Fig 6 .    The FMECA of this sub- circuit is given below. a) If Pin 19 of Comparator UA is s-a-1: The Decoder UD and Buffer UC will not be enabled. Processor cannot read ID andID* of Input Card. b) If pin 19 of Comparator UA is s-a-0: The fault will not be detected. c) If any Input Pin of P or Q Comparator of UA is s-a-0 / s-a-1 : Software data sent by Processor will not match with Hardware data from the Backplane. Failure is same as (a). d) If any Pull- up resistor for Backplane is Open: The corresponding Pin may float to either 0 or  1. Depending on that the Hardware and Software addresses may or may not match. e) If any Input Pin of Buffer UB is s-a-0 or s-a-1. Software data will be faulty and may or may not match with Hardware data. f) If Pin 19 of Bus Driver UC is s-a-1: UC will not be enabled. Card ID and ID* cannot be read. g) f) If Pin 19 of Bus Driver UC is s-a-0 : UC will be permanently enabled and the fault will remain undetected while accessing the Card. h) If Pin 1of Bus Driver UC is s-a-1 : UC will not allow reading Card ID and ID*. i) if any Data Pin of Bus Driver UC is s-a-0 or s-a-1 : Processor will get wrong ID and ID*. j) If Pins 1 and 19 of Buffers UE or UF are s-a-1 : Processor will not get ID or ID* depending on whether UE or UF has got the fault. j) If Pins 1 and 19 of Buffers UE or UF are s-a-0 : UE or UF will be permanently enabled . There will be Bus contention while reading ID and ID*.    

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Somnath Pal -
Posted 2 years ago

QUANTIFIED RAMS BASED RAILWAY ASSET MANAGEMENT

Rail Asset

  Railway Asset Management provides Sustainable Infrastructures through evidence-based decision making to achieve the optimum performance with Economic benefit while ensuring Safety and Integrity. It covers defining Asset Management Policy, Strategy and Framework. Key factors to consider are the physical deterioration, obsolescence, operation and maintenance of the system. Corrective Actions are based on management Data Reviews. Asset Managers must perform Risk Analysis and Predictive Analysis for Maintenance planning. In addition, a Qualitative Vulnerability Analysis and Managerial Oversight Risk Analysis should be performed to evaluate System Safety Robustness.  After defining the System Reliability, Reliability Allocation to sub-systems are fixed and various Design and Manufacture criterions are followed with trade-off between Performance and Service life-cycle Cost. Failure probabilities are calculated after Mitigation of critical Failure Modes. Cost models on maintenance optimization can be based on Markov model with Inspection and Replacement policy. Incentive on improved Reliability and Supply of specific Reliability Data for the Equipment must be implied in Supply Contract, considering other performance aspects.  Acceptance Testing should comply with Reliability Targets and specify Accelerated Stress Test Duration, including Burn-in periods, if any. Maximum Likelihood Estimation for Failure is calculated before Asset acceptance. While increasing Reliability, Preventive Maintenance reduces Availability and might introduce new failures. So, Predictive Maintenance using Diagnostics and Prognostics is a better Option. Comparisons between Repair and Renewal are chosen to maximize Availability. MTTR must comply with 95% Confidence that Repairs are performed within defined duration. Optimum Inspection Interval must be calculated from Failure Rates, Inspection duration and Repair time. Adequacy of Spare Parts and Location of Stores, whether Centralized or Distributed, are to be specified after calculations to provide maximum Availability.  Reliability Growth testing must be done to verify stipulated MTTF. To avoid any lapse during On-site Maintenance Activities due to Human Errors, specific Checklists, Maintenance Tools and, Drawings must be available. Proper updated Training is mandatory for the Concerned men-at-site. Cloud-based Intelligent Safety Asset Management can implement Expert Systems, Video Conferencing with Experts during emergency and Video Surveillance of Construction Sites. Finally, Asset Management Audits check whether the specified strategies are being followed.

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Suman Pathak -
Posted 12 months ago

POWER QUALITY ISSUES IN RAILWAY ELECTRIFICATION

Rail Electrification

  POWER QUALITY ISSUES IN RAILWAY ELECTRIFICATION The power quality issues through electric railway development are overviewed as follows :    Voltage Unbalance Voltage imbalance (also called voltage unbalance) is defined as the maximum deviation from the average of the three-phase voltages or currents, divided by the average of the three-phase voltages or currents, expressed in percent. The most frequent problems of voltages are associated with their magnitudes. The major problem is unbalanced currents produce unbalanced voltages. Traction motors and other related loads in trains are designed to function properly with reduced voltage amplitude by 24% or increased amplitudes by 10% than the nominal voltage of electric railroad drives. System imbalance System imbalance is the most serious problem in electric railway power quality because most trains are single phase, and a single-phase load produces a current NSC (Negative Sequence Current) as much as a PSC (Positive Sequence Current). A new traction power supply system adopting a single-phase traction transformer and active power flow controller (PFC) is proposed. In the new system, the power quality problems caused by single-phase traction load are solved on the grid side and the continuous power can be Arcing The interaction between the pantograph/catenary of overhead systems or between brushes and the third or fourth rail causes arcs because of dynamic latitudinal tolerance between the wheels and rail. Arcs will occur, which can distort voltages and currents and produce a transient dc component in the ac systems causing a breakdown of dielectrics. Flicker As the train passes between two adjacent substations voltage sag may happen and affect other customers electrical light performance so-called flicker. EMI/EMC The movement of rolling stock along an electrified track produces Electromagnetic interference in the system. EMC covers a wide range of phenomena, including inductive noise in parallel communication lines, impulse noise from lightning and traction transients, the production of hazardous voltage under step and touch conditions, and the appearance of stray currents. EMI and EMC are very complicated for high-speed railway systems. Nowadays, the investigation in EMI/EMC high-speed railway is highly relying on simulation and measurement. Waveform Distortion Waveform distortion is defined as a steady-state deviation from an ideal sine wave of power frequency. There are five primary types of waveform distortion :  1. DC offset     The presence of a dc voltage or current in an ac power system is termed dc offset  2. Notching    Notching is a periodic voltage disturbance caused by the normal operation of power electronic   devices when current is commutated from one phase to another.    3. Noise    Noise is the unwanted electrical signal with broadband spectral content lower than 200 kHz  superimposed upon the power system voltage or current in phase conductors, or found on neutral  conductors or signal lines.   4. Interharmonics  Voltages or currents having frequency components that are not integer multiples of the frequency  at which the supply system is designed to operate (e.g., 50 or 60 Hz) are called inter harmonics.   5. Harmonics Harmonics can be best described as the shape or characteristics of a voltage or current waveform relative to its fundamental frequency. The ideal power source for all power systems is smooth sinusoidal waves. These perfect sinewaves do not contain harmonics. When waveforms deviate from a sinewave shape, they contain harmonics. These current harmonics distort the voltage waveform and create distortion in the power system which can cause many problems. In short (Harmonics are sinusoidal voltages or currents having frequencies that are integer multiples of the frequency at which the supply system is designed to operate.) Types of Harmonics: Odd and Even Order Harmonics: As their names suggest, odd harmonics have odd numbers (e.g., 3, 5, 7, 9, 11) , and even harmonics have even numbers (e.g., 2, 4, 6, 8, 10) . Harmonic number 1 is assigned to the fundamental frequency component of the periodic wave. Harmonic number 0 represents the constant or DC component of the waveform. The DC component is the net difference between the positive and negative halves of one complete waveform cycle. Total Harmonic Distortion (THD) is defined as the measurement of the harmonic distortion present in a waveform. The power quality of a power system is inversely proportional to THD. More harmonic distortion in the system, lower will be the power quality and vice versa. THD is equal to the ratio of the RMS harmonic content to the fundamental:   Where Vn-rms is the RMS voltage of nth harmonic in the signal and Vfund-rms is the RMS voltage of the fundamental frequency. The Destructive Effects of Harmonic Distortion A power system’s ability to perform at optimal levels is compromised when harmonic distortion enters the system. It creates inefficiencies in equipment operations due to the increased need for power consumption. The increase of overall current required creates higher installation and utility costs, heating, and decreasing profitability. Harmonics in Electrified Railways It is well known that the rapid spread of power electronics brought along not only great advantages but also some drawbacks as they are the main sources of harmonics and voltage waveform distortion. Harmonic has emerged as a matter of great interest for electrical power system engineering. The electrified railway is one of the main harmonic sources in utility. Because electrified railway is supplied by High Voltage (HV) power system directly, lots of harmonic (mainly including 3rd, 5th, and 7th) produced by electric locomotive penetrate in the whole utility from HV. Compared with normal load, the most characteristics of traction are random time-varying and non-symmetry. So, the harmonic of traction load is very different from the normal load of utility. In an electrified railroad, the traction power is delivered to the catenary by substations, which in turn receive their supply from the utility network. For the electric utility transmission systems, the alternating current catenary is an unfavorable consumer.  Two major reasons for this are: i)    the catenary is a single-phase load, which power consumption unbalances the main supply three-phase system, ii)   the use of power electronics converters to drive traction motors, generates harmonic currents that perturb interconnection busbar voltage. Basically, the power quality issues in railway electrification systems include the studies of the influence of traction loads on three-phase utility systems. Most of the high-speed trains are single-phase loads. Due to a large amount of power electronics application to the motor driving circuits of trains, they contribute to the high harmonic currents flowing to the railway catenary system.  Traction load is varying dynamically, and arcs may occur because of pantograph/catenary and switching actions. Modern drive trains rely on power electronic converters combined with transformers, which inject low amounts of current harmonics into the supply system. Therefore, power quality must be considered in all aspects of the design for every system dealing with electric power systems. Some especially connected transformers are widely used, such as V-V, Scott, Le Blanc, and Modified Woodbridge connection schemes have been utilized in traction substations to compensate for negative sequence current (NSC) of the grid-side. Due to the nature of time-varying traction loads, it is almost impossible to compensate the whole NSC in all loading conditions.  Passive filters have been adapted to suppress harmonics in electrical railway systems. Among derivations of filters, a C-type filter (CTF) introduces no power loss at the fundamental. frequency and performs as a first-order high-pass filter at tuned resonance frequency. Accordingly, the CTF is generally used to mitigate high-order harmonics caused by the PWM converters of the traction trains and prevent harmonic resonance. Although passive devices are affordable with a simple configuration, their performance is not satisfactory when operational conditions are varying. Therefore, active devices in AC electric railways have been proposed to resolve this issue. Static VAR compensators (SVC ) and static synchronous compensators (STATCOM) were proposed to compensate the load reactive power of trains dynamically. Since electric locomotives introduce harmonic contents, there is no chance to compensate harmonics by these devices, concurrently.  Many other strategies have been also proposed for power quality improvement in electric railways, investigated in a comprehensive historical perspective. Nowadays, power quality improvement strategies have developed to a mature degree for new electric railway systems, among which Railway static Power Conditioners (RPC) and its alternatives (e. g. APQC, HBRPC, HPQC) have the main place.  These compensation schemes are connected to the TSS secondary, as shown in Fig. , and theoretically operate based on instantaneous active/reactive power theory, in which the three-phase currents at the TSS primary side are supposed to be:  (i)    three-phase symmetrical, (ii)    fully sinusoidal with no relevant harmonic content (iii)    aligned with the three-phase voltage featuring negligible reactive power.  Thereafter, the difference between the load currents and the ideal currents must be generated by the compensator, called compensation currents. The compensator operates as an independent three-phase current source, generating the desired compensation currents. The RPC consists of two single-phase back-to-back converters sharing the same DC-link capacitor through which active and reactive power are applied compensates voltage, NSC, total harmonic distortions (THD), and PF simultaneously and each AC side of inverters are connected to the two phases of the secondary side of feeding transformer, main phase, and teaser, respectively. These inverters work as effective power balancers and reactive power compensators. For example, if a load of the main phase is larger than that of the teaser, the RPC transfers effective power from the teaser bus to the main phase bus. This system works to balance the effective power of different phases and compensate for reactive power to reduce voltage unbalance and fluctuation. The various structures of the RPC such as active power quality conditioner (APQC), half-bridge RPC (HBRPC) and Hybrid power quality conditioner (HPQC) were presented. These devices can perform at a full compensating method which results in grid-side power factor unity, zero current unbalance, and harmonics.   DIFFERENT COMPENSATORS USED IN SCOTT CO-PHASE SYSTEM  Hazards of Poor Power Quality Problems in Railways Impacts on Signaling and Communications: Track circuits are designed to work with a special frequency that must not have any interference with the power frequency. But in presence of harmonics, communication signals may be affected by harmonic frequencies, resulting in erroneous signals and faulty train positioning, which lead to a disaster. Also, high-order harmonics may cause an interference problem between communication and power systems. Malfunction of the protective system: Protection relays may operate incorrectly in the presence of harmonics and NSCs of currents and voltages. Traction load injects many harmonics and NSCs resulting in the malfunction of the protective system. Decreased Utilization Factor: Since the traction load is a large single-phase load, it results in high current NSCs, which will flow in only two phases, and it decreases the utilization factor of the transmission line. Incorrect Operation of Transmission Line Control Systems: Voltages and currents sampling is based on fundamental components of either voltage or current. Every control system in the transmission line would work not appropriately because traction loads inject large amounts of harmonics and NSC current into the transmission lines.     References: " IEEE Paper 10.1109/TIE.2014.2386794”, IEEE Paper 10.1109/TVT.2017.2661820, IEEE Std 519-1992    

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Kathy Shen -
Posted 10 months ago

Pantograph CCTV Intelligent Analysis System for rolling stock

Communication Systems

  1. Overview By the arrangement of the Ministry of Machinery and Vehicles of the National Railway Group on the intelligent analysis of the pantograph video monitoring system, the existing pantograph video monitoring system intelligently analyses the installation requirements, identifies pantograph mechanical structure abnormalities, electrical faults, and other problems, and assists mechanics in judging pantograph faults. Through the analysis of the failure mode of the existing vehicle and the vehicle protection logic, mainly for pantograph failures that cannot be detected by the car itself, such as pantograph tilt, pantograph structure deformation, etc. Such failures are not easily identified during operation and lead to more severe consequences. The intelligent analysis function of the pantograph video monitoring system can analyze the pantograph video monitoring images, identify pantograph faults and make alarm prompts to assist the mechanic in judging and taking effective measures to avoid more significant hazards. 2. Pantograph CCTV System composition The pantograph CCTV system is used to monitor the operational status of the pantographs and contact network on the roof of the train in real-time during operation. The intelligent analysis function adds intelligent identification technology to the original video monitoring system to achieve automatic real-time identification of abnormal pantograph conditions. Save videos of the working state of the pantographs during train operation and pictures of structural abnormalities in the pantographs to provide supplementary surveillance videos and analysis images for the accompanying mechanics to deal with abnormal bow network faults. The intelligent analysis function of the pantograph CCTV system for rolling stock consists of the following main components: pantograph video monitoring server, intelligent analysis host, pantograph camera, and monitoring screen. 3. Application conditions of the intelligent analysis function of the pantograph CCTV system   The intelligent analysis function of the pantograph video monitoring system mainly identifies pantograph faults during vehicle operation. For significant pantograph faults, such as ruptured ducts and dislodged carbon skids, the pantograph will be automatically lowered without further judgment and operation by the mechanic. This intelligent analysis function alerts for bow abnormalities that are not easily detected directly, such as pantograph tilting and pantograph structural deformation, with priority given to identifying bow structural abnormalities as they have the most severe impact. Combined with the technical item analysis of pantograph faults in the high voltage system of the rolling stock, the application items for which the intelligent analysis function of the pantograph video monitoring system assists the mechanic in making judgments were identified as follows. 1. The pantograph is tilted during operation. At this time, the pantograph duct does not break and will not automatically lower the bow. If no alarm is provided, the tilted pantograph may be pulled by the contact network or knocked out by other foreign objects, causing severe secondary damage, so fault identification and alarm are required under this working condition. 2. Structural deformation occurs during the pantograph operation; the types of structural deformation include missing bow angles and bending deformation of the bow structure, etc., when the duct is not broken. Alarm failure may result in problems such as drilling bows, so fault identification and alarming are required for this condition. 3. Foreign objects caught in the pantograph during operation. Identification and alarm for foreign objects hanging on the bow structure and identification and notice for foreign objects on the support frame. 4. When large sparks are generated during pantograph operation, and the sparks occur in the working area, intelligent analysis functions are required to effectively identify the large sparks and provide alarms to avoid secondary accidents. Tiny sparks generated during operation are not identified, and alarm for the time being because they are not a significant hazard. 5. There is a small amount of dirt in the pantograph CCTV system camera, with a small portion at the bow structure captured by the camera when the intelligent analysis is required to allow for chunking and identification without interference from foreign objects. 4. Pantograph structure anomaly identification 4.1 Pantograph structure deformation alarm There is a small amount of dirt in the pantograph CCTV system camera, with a small portion at the bow structure captured by the camera when the intelligent analysis is required to allow for chunking and identification without interference from foreign objects.                                                           Picture of pantograph in normal condition After running for some time, the vehicle pantograph is subjected to structural deformation by foreign object impact; it is necessary to effectively identify this type of fault and alarm through the pantograph video monitoring system; the identification picture is shown below.                                                         Pantograph structure failure picture 4.2 Pantograph tilt alarm Pantograph tilt faults can occur during operation and need to be brought to the mechanic's attention in time for judgment and action. However, the structure of the pantograph and the position of the pantograph camera installed on different models are different, so the decision of the tilt angle of the pantograph is different. Combined with the relevant video of the pantograph tilt, the tilt angle of the alarm needs to be given.                                                 Intelligent identification of pantograph tilt angle pictures 4.3 Pantograph angle break alarm There are two scenarios for pantograph angle breakage, one in which the angle is broken and suspended but not dislodged, and one in which the angle is broken and dislodged. Both scenarios require testing the bow integrity and sending an alarm signal to the monitoring screen when the pantograph form is incomplete. The difference lies in the trade-off threshold settings needed in both cases to reduce the rate of missed alarms. It also needs to be combined with video testing to define that an image above 40 frames in 3 seconds is a fault that will send an alarm condition.                                                            Pictures of the pantograph lowering process   (1)Bow horn fracture not detached The situation is as shown in the diagram below when the pantograph angle is broken and not dislodged from the fault.                                             Picture of pantograph with broken bow angle not dislodged Intelligent analysis of such situations requires correct identification of faults and alarms and actual testing of breakage without dislodging video detection. (2)Bow angle completely broken This type of pantograph fault needs to be identified when a complete break in the pantograph arch angle occurs, as follows.                                             Intelligent identification of complete pantograph angle breakage Intelligent analysis of such situations requires correct identification of faults and alarms and actual testing of breakage without dislodging video detection.   4.4 Pantograph foreign object intrusion alarm False alarms caused by various factors are considered when the pantograph intelligent analysis mainframe identifies foreign object intrusion faults in the pantograph. Analysis from the intrusion results currently only identifies foreign object intrusion faults hanging from the bow for a long time. (1)Pantograph body For the intrusion of foreign objects into the bow of the pantograph, it is necessary to identify whether there is a foreign object intrusion, as shown in the diagram below, which requires the apparent detection of a foreign object in a plastic bag hanging from the pantograph of the “Fuxing” D1702.                        Intelligent identification of foreign objects hanging from the pantograph body 4.5 Pantograph spark alarm Currently, tiny pantograph sparks are not analyzed for identification due to their minor impact on vehicle safety. Pantograph intelligent analysis of pantograph sparks identifies only significant spark faults (Spark area > half of the pantograph head area; this indicator can be modified for configuration). The spark is judged to be in the working area of the carbon skid (x1 to x2, as shown in the picture below) to avoid false alarms. The large pantograph sparks intelligent identification alarm result is shown in the following picture of the large spark intelligent identification alarm.                                Image of the coordinates of the area where the spark occurred                                  Pantograph large spark intelligent identification alarm result picture 5.Intelligent pantograph fault recognition and alarm for particular operating conditions In opening the intelligent analysis function of the pantograph video monitoring system, special working conditions can have a significant impact on the intelligent analysis function, resulting in missed and false alarms. The following special conditions are required. 5.1 Tunnel mode alarm During the process of entering and exiting the tunnel and running in the tunnel, the camera's exposure and the influence of the environment in the tunnel will affect the intelligent analysis function, as follows. When entering and leaving the tunnel, algorithms need to be designed to recognize the tunnel entry and exit patterns and filter out false exposure alarms for the entry and exit tunnel entrance process. The diagram below shows that the exposure images need to be filtered out, and no warnings are made.                                                 Instant exposure picture of entering the tunnel In the tunnel, it is necessary to identify whether the current environment is suitable for detection, i.e., whether the pantograph video monitoring screen is blurred or not. If the screen is blurred due to insufficient fill light intensity or fill light failure, then the intelligent identification detection function is switched off. If it is not confusing, then detection is activated, as shown in the picture of the system generally operating in the tunnel. In addition, false alarm scenarios caused by reflections from fill lights are recommended to be included in the category of unsuitable detection, with the alarm function turned off, as shown in the picture of the bow blur caused by reflections from fill lights in the tunnel.                                                 Pictures of the system in operation in the tunnel                                          Image of bow blur caused by reflections from fill light in the tunnel 5.2 Background mode alarm (1)Background factors such as bridges, power supply equipment Interference caused by background factors such as bridges, power supply equipment, etc., are a few frames that will occasionally be detected as anomalies during intelligent analysis. The alarm will be triggered when there is an anomaly greater than a certain number of frames so that false images can be effectively filtered out. The specific algorithm needs to be set up in conjunction with the vehicle's speed, the time consumed by the car to pass background objects at different rates (i.e., the number of frames) is counted, and the thresholds are optimized to exclude such interference ultimately. For example, by analyzing the background railings shown below, it was found that the train took up a total of about 4 frames as it passed through the above background facilities. The pantograph detection result is normal after 4 frames, so set that for this type of railing background. It is possible to set more than 20 frames in 1 second for normal recognition without alarm.                                                          Background pattern interference picture (2)Background factors for train stops For train stops, the speed threshold needs to be set to 0, i.e., the intelligent identification function is switched off when the speed is 0. The pantograph video monitoring picture of the train stop is shown below. The image on the left shows background interference, which will give rise to false alarms. In the picture on the right, if the pantograph stops on the railing behind the image after the train has ceased to produce an overlap, false alarms will occur, so setting the speed to 0 when the intelligent analysis function is switched off will filter out such interference.                                             Video surveillance images of pantographs at train stops (3)Train entry contextual factors During the train's progress, the intelligent analysis function can be affected by false alarms due to changes in the background of the station. Due to the low-speed state, pantograph abnormalities have less impact on vehicle operation safety, and the low-speed state is less likely to cause abnormal pantograph structure problems. A certain speed threshold must be set to shield the station from false interference alarms. The pantograph video monitoring intelligent analysis function is switched off below a specific operating speed. According to the vehicle in and out of the station speed limit, tentatively set lower than 40 km / h, the speed threshold can be adjusted according to the application of the analysis to minimize the occurrence of false alarm problems. 5.3 Dirty mode alarm The dirty mode affects the clarity of the pantograph CCTV system camera and thus the alarm of the intelligent identification function. Intelligent analysis can be switched off directly to reduce false alarms for dirty stains with a significant impact, such as sand, dust, heavy rain, or snow. For less impactful dirt, such as small smear spots, false alarms need to be reduced. The judgment of the influence of dirt can be realized by identifying whether the video picture is blurred.                                                     Pantograph video image clarity comparison image The amount of dirty intrusion needs to be identified for judgment. For example, as shown in the diagram below, if you set the intelligent analysis to turn off when the rainwater intrusion exceeds 30%. The graph below does not identify the pantograph as a whole, i.e., rainwater soiling encroaches on the pantograph area by more than 30%. The rain is judged to be too heavy, and the intelligent analysis is switched off. If the rainwater dirt encroaching on the pantograph area is less than a certain threshold, the intelligent identification function is not switched off.                                      Pantograph video surveillance images under heavy rain conditions For cases where the soiling is minor, the video image is identified as edge soiled, and the overall structure of the bow is not affected; therefore, no alarm is made, as shown below.                                        Pictures of pantograph video surveillance affected by dirty edges For more minor dirty cases, the dirty area of the lens is primarily fixed.   6.Client   when the intelligent analysis function detects an abnormality in the pantograph, an alarm box pops up directly on the interface of the pantograph video monitoring screen, which contains the type of pantograph fault and the fault picture. At the same time, you can click on the "Associated Video" button in the alarm box to call and play the 2-minute video where the fault picture is located (1min before and 1min after the fault alarm picture), as shown in the figure below.                                            Pantograph monitoring screen fault video alarm picture    

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