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  Introduction
This is a modern system for tram depot operation control enabling control of tram depot operations, central points control, that brings better general real-time and past view of events in the tram depot and principally increases operational safety. Using the system will also eliminate the proportion of unqualified work of employees and significantly increase the tram depot work productivity. The system can also evaluate data on operations of individual trams to achieve more efficient service and maintenance by evaluating the data. It also allows processing and inspection of many other technological devices in the tram depot (tram-wash, heating of points, inspection of voltage-free condition of selected stretches of trolley wires etc.), whose function is very important from the operational point of view. In collaboration with the tram system operator, it is necessary to correctly define the dossier and to accommodate the system to local conditions in order to create an economical proposal and correct functioning of the system. Readiness for such collaboration and open discussion with the partner is an essential condition and commonplace on our side.
Construction of new tram depots and reconstruction of existing ones without implementation of similar systems is a thing of the past in developed countries. For example, all tram depots in the new federal states of Germany were so equipped in the last ten years and in newly constructed operations in Europe, such systems are part of the projects. Central and Eastern Europe are also not lagging behind; for example in the Czech Republic, the system is in operation in Liberec and being built in Prague. Recently, the system has been implemented for example in a tram depot for 200 trams in Moscow, Russia.
Basic system features
1. Monitoring and tram movement control in the depot
2. Remote controlling of tram paths from control computer or portable transmitter
3. Display of voltage conditions in the trolley wires inside hall (in relation to other devices)
4. Automatic gate opening in case there is a relation to their suitable control and safety systems
5. Archiving of all data with possibility of recalling tram movement at selected times
Description
During their movement in the depot, the trams are monitored using radio signal receivers and resonance rail circuits located before and after every electrically controlled point. The receiver identifies the number of the transmitter installed on the tram. Assigning of the transmitters to the trams according to their registration numbers is saved in the control computer database. The control computer screen displays the trams with their registration numbers. The resonance rail circuit only indicates presence of the tram in a given stretch. The main purpose of the circuit is to prevent uncalled manipulation at the moment of tram travel. The tram movement control is enabled by the display panels and traffic semaphores. More information for tram drivers is provided by trichromatic numerical indicators. The tram traffic controller controls the movement of the trams in the depot and operation of the tram paths from the control computer. Control of the tram paths is also possible using a small manual transmitter available to the depot handling driver. Under standard conditions, this function is disabled unless enabled by the tram traffic operator.
Upon a tram arriving at the depot, it is registered by the receivers located in front of the depot entry. The tram is identified and displayed on the screen by the transmitter number installed on the tram. The display panel and the traffic semaphore are installed at the depot entry. The panel displays the next ride direction using a symbol or number and the traffic semaphore enables or disables further travel as required by the tram traffic operator. The same equipment is installed in other suitable places according to track system arrangement and operational arrangement in the depot. At each panel, the tram can be stopped by the traffic semaphore and the correct tram path for further travel can be set. If the tram path is already set correctly, the traffic semaphores can give the vehicle free way all along the path length. The tram, after inspection procedures and washing or repair, if appropriate is queued to a defined track and place. To depart, the trams are queued to depart in sequence from different rails and not successively. The trams usually depart by time according to timetables. The departure can also be controlled by the tram traffic operator using the traffic semaphores or automatically in relation to the timetables. The numerical indicators are located above the tracks and show setting of the tram paths by changing colour. Normally, a red number showing the track number is on the indicators. Upon setting of the train path, the colour changes to green. If the train path is set and the trolley wire in the hall is not under voltage, the number turns yellow. The last function depends on signalling of the voltage-free condition of the trolley wires with which the system has to be connected. If the depot is equipped with suitable systems for opening and securing the gates, the control system can also ensure their opening upon approach of a tram.
All data are saved and regularly archived on daily basis by a backup unit. Using sophisticated software, viewing of depot events as they have occurred, successively day-by-day, is possible. Statistical data can be processed as well, if required.
The system is highly flexible and its features and functions can be modified according to customer requirements during the project phase. Interconnecting with other devices used in the depot can be carried out as well.
List of the Basic Parts
1. PC - control computer
2. RCRS - communication and department distributor
3. RNRS - power supply distributor
4. RV - distributor for points and receivers control
5. RP - distributor for radio signal receivers
6. RC - distributor for numerical indicators and traffic semaphores
7. RS - distributor of voltage-free conditions signalling
8. ZP - display panel
9. DN - traffic semaphore
10. PRI - radio signals receiver
11. CU - numerical indicator
12. KO - safeguarding resonance rail circuit
13. EHP - electro-hydraulic driven points mechanism
14. RMT - points heating control distributor
15. RT - points heating distributors
16. TRAMVYS 6K - radio signal transmitter installed on trams
Division into functional groups
The points control system and trams monitoring operates as a network of elements (stations) communicating with the central PC via an RCRS distributor. The communication cables lead to RCRS in star-like topography, i.e. from each distributor or the display panel. At both ends, each cable terminates in a high-voltage (8 kV) galvanic RS485/RS232 separator - converter, which enables the communication lines to be connected to one PC port without any impedance problems upon direct connection of cables. The transfer rate is 9600 Bd. Each communicating element (a programmable automatic machine, a group of receiver decoders, the display panel) is independently connected up to an RCRS communication distributor in the control room and here, they are interconnected to individual groups connected to the 16xRS-232 communication multi-port card in the central PC.
The points heating sub-system operates as an independent network of programmable automatic machines where only one automatic machine in the points heating control system is connected to the PC. Only this control distributor is equipped with two meteorological units and a manual control panel. Manual control is available to the tram traffic operator. The communication interconnection of RT satellites with the RMT control distributor is bus-like; RS485 is used again, although its baud rate is reduced to 2400. In the distributors, the communication cables are individually connected to CP4x2 overvoltage protected terminals and their parallel connection is made on high-voltage insulator/converter sockets over phone-connector cables, so the connection can easily be disconnected and tested.
Description of Individual Basic Parts
The points control system and trams monitoring
1. PC - the central control PC located in the control room. The PC is a computer built and equipped for a specific purpose. Some important parts are doubled. Large-screen monitors (22") are connected to the PC and show current status of the tram depot in a tabular form. The PC is equipped with its own UPS and multi-port card with 16 RS232 channels. The channels are connected to the RCRS communication distributor, where they are optically separated and transferred to RS485 and connected to the communication elements in the tram depot.
2. RCRS - the control system communication distributor is designed to connect the communication cables from all communicating distributors, the tram depot system elements and the distributor for points heating. The system includes a high-voltage (8 kV) insulator/ converter for each communication channel. Then the converters are grouped and connected to the multi-port communication PC card. The communication network is arranged so that each communication element - the depot station - has its own communication port connector terminating in RCRS. The structure of interconnecting input RS485 ports to smaller number of RS232 channels leading to the PC (with the galvanic separation and the level transfer) is created in the RCRS only. In the depot-located distributors, the RS485 channels are not combined and all are individually led to RCRS. To a certain extent, the structure can be changed if necessary. There is also one reserve group with its own RS232 channel intended for testing or servicing purposes, to which any station or more stations can be connected if necessary. The station addresses are unique; they can theoretically all be connected to one RS232communication port. The interconnection of individual RS232 channels (optically insulated and transferred to RS485) with termination of the stations communication cables is made using four-core cables with RJ12 terminals (commonly used for phones). With their switching over, a defective communication channel or port can be detected in case of communication errors and the network structure can be modified as well, if necessary.
One exception is the points heating control subsystem, where only the RMT distributor is connected to RCRS using one channel only. Then, its satellite RT distributors are RMT connected using their own local sub-network (RS485 too) and are not directly reachable from the center. For heating purposes, where a high baud rate is not required, this structure is fully suitable.
3. RNRS - the control system power supply distributor, used for feeding all the depot elements, apart from heaters for the points. The control circuits (PLC, receiver systems etc.) are power supplied from single-phase circuits of 220 V. Motors of the electro-hydraulic driven point mechanisms are power supplied from three-phase circuits of 380 V. Each distributor has an independently fused current circuit.
4. RV - as standard, the distributor for points control is capable of controlling up to six points with twelve track circuits and of serving up to eight radio signal receivers. The point systems can be simple with two position sensors or with control throw rods and six position sensors. Two track circuits (connected to PLC via complementary signals) are assigned to each point. By means of hardware, the distributor is interlocked so that it is not possible to control the points if one or more track circuits are blocked and activation of the track circuit does not terminate already commenced controlling of the points. What's more, the relay used in the interlock is monitored.
The distributor has two independent RS 485 communication lines, one for the points system and the other for the receivers system.
There are also options for the distributors that have one or two track circuits in the satellite distributor and outputs of the track circuits are brought to the RV distributor. This solution is necessary for cases where the points are too far away from the distributor, because the track circuit loop feeds are length-limited. However, these options do not in any way impact on the control method. All the RV distributors and points appear the same to the control system.
The distributor has an independent single-phase and three-phase power supply. The single-phase 220 V power supply feeds the control and communication system and the group of receivers. The three-phase 380 V power supply feeds the points motors only.
5. RP - the distributors include two groups of radio signal decoders. To each group, maximally eight receivers, i.e. max. 16 receivers per one distributor can be connected. Each group has its own RS485 communication line. They use single-phase 220 V power supply.
6. RC - the distributor for control of lighting single-digit or double-digit numbers consisting of individual bicolour (red/green) LED modules. The figures are fixed. The power source module in the distributor corresponds to each number when the current is set to a specific number (depends on number of modules in the figure). The distributor also enables connection to the traffic semaphores. The distributor has one RS 485 communication line. It uses single-phase 220 V power supply.
7. RS - the distributor arranges processing and high-voltage separation of signals brought from voltage-free conditions in the trolley wires in the depot. The distributor has one RS 485 communication line. It uses single-phase 220 V power supply.
8. ZP- ZP is the display panel consisting of matrix display, 8 vertical and 16 horizontal dots (red LED 5 mm Hewlett Packard) located in a plastic cabinet. The complete ZP does not include a programmable automatic machine but a microcomputer. It uses one RS 485 line to communicate with the PC using the same protocol as the other distributors. It uses single-phase 220 V power supply only. The traffic semaphore can be connected to the ZP.
9. DN - the traffic semaphore located in a plastic cover consisting of orange LED modules. Powered by 24 V DC from the ZP or the RC.
10. PRI - the PRIPAT radio signals receiver, in a plastic tube with 4-pin connector. Located in the ground to the right of the track in a plastic cabinet; communication and power supply using shielded four-core communication cable. Frequency: 433.9 or 868.35 MHz. Range: approximately 2 m.
11. CU - the numerical indicator consisting of LED modules. The number is either red and green or also yellow. The CUs are connected to the RC. Apart from the LED modules, no other electronics are supplied. Powered by low voltage from the current sources located in the RC.
12. KO - the resonance circuit consisting of rails located close to points. The circuit serves to safeguard the tram path against uncalled operation of the points and to monitor movement of the trams. Only cable connections and a capacitor are in the track system. The electronics concentrated in the plug-in module are located in the RV distributor, and are independent for each resonance rail circuit.
13. EHP - the electro-hydraulic driven points mechanism does not use contact line voltage (600V DC), three-phase 3 x 380 V voltage from the depot grid. Two hydraulic motors provide movement to the points mechanism. The hydro-generator connected to an asynchronous engine of 500W output provides pressure to the hydraulic liquid. To manually set the points mechanism, a branch with a short-circuit valve is provided. Under normal conditions, the branch is conductible and forms a bypass hydro-generator path, which allows relocation of the hydraulic liquid between the hydraulic motors upon manual setting of the points mechanism using a lever. Under operation of the device, the branch is short-circuited by the valve. The hydraulic liquid is environmentally friendly hydraulic oil.
14. TRAMVYS 6K - is the transmitter used for controlling tram points via a radio signal and for transmitting certain additional information from trams to the points control system or to the depot control system. The transmitter power is low and its frequency is set at 433.9 or 868.35 MHz. Range: approximately 2 m. The TRAMVYS 6K is installed under the front right-hand tram stairs, as far as possible from the tram axis and as close as possible to the tracks. The transmitter box is installed in a vertical position and its inlet is orientated to the left of the front of the tram. Control is carried out using the tram's computer or a three-pole rotary switch located on the tram driver's panel used for travel direction selection.
The control carriage (the first carriage of the tram set) permanently transmits a signal according to the rotary switch position in order to operate the points on the path and to provide information about the tram travel direction (forwards or backwards) and identification number. The transmitter of the controlled carriage (the second carriage of the tram set) transmits information about travel direction (forwards or backwards) and identification number only. The depot control systems do not use the travel direction (left, straight, right). Based on the ID number of the tram, the tram path is either set automatically, by the PC operator or via the portable transmitter.
The points heating subsystem
15. RMT - the points heating control distribution with two independent meteorological units. Each unit includes a heated air humidity sensor (a small roofed structure), outdoor temperature thermometer, heated points temperature thermometer and check thermometer for measuring the roof temperature. It contains two independent high-voltage separated RS 485 communication lines; one for connection to the higher control system and the other for connection to the RT satellites. The latter line is led to two communication cables (the RMT is connected to the two satellites positioned approximately in the centre of the bus). The RMT contains buttons for local control and the remote control panel, independent of the data communication with the higher PC, and control lights can be connected. It uses single-phase 220 V power supply.
16. RT - the satellite distributor for heating up to 12 points. It contains a contactor for the heating rods, current protectors and current relays to control the current in the heating rods. It also includes a switch to directly turn the heating on, without any regulation, independently of the control system function. For each points tongue, a heater of approximate power 300 - 400W/1 m of length is connected via an independent cable. The distributors are connected to the RMT distributor using high-voltage separated RS 485 lines in two branches. Power supply for heating rods is three-phase 380 V, directly from the switchboard room. Power supply for the control circuits is single-phase 220 V.
Communication lines diagram - example
Power supply diagram - example
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