SYSTEM DETAILS OF A GENERAL SCADA SYSTEM

The overall supervisory remote control and data acquisition system designed for 25 KV traction supply essentially consists of :-

1.Master controller of RCF/Front End Processed (F.E.P)
2.Remote Controller at TSS, SP and SSP.

Functionally the provided at the remote control centre (RCC) performs the functions required for sending telecommands receiving telesignals and telemeter purpose.

The F.E.P is the heart of the system and master controller is used as mimic driver. This originates the interrogating messages during the normal scan sequence mode, or the control messages during the control mode. These serial messages are transmitted to the remote controller through modem. It also performs formatting and parity generation operations.

The F.E.P and SN -73 enables in maintaining the scan time within reasonable limits, and also provide large amount of date processing, data logging and Supervisory Control Operations through workstation keyboard.

A mimic diagram board can be connected through suitable interface to the master,

The MDB workstation provides a visual indication of state of the equipment at various stations.

The remote controller are ruggedised stand alone units, capable of performing task of acquisition monitoring and control required at TSS, SP and SSP. These act as intelligent slaves to the master at RCC, thereby reducing processing requirements of the master and the communication overhead. The remote controller is a microprocessor based data acquisition and control system capable of accepting analog as well as digital inputs. The remote controller has a communication interface which allows it to communicate with the master over telephone lines. The operation is half duplex, with FSK modulation and nominally at 600 baud-rate.

The status of the circuit breakers, isolators, etc. are given by the digital input modules. The system is isolated from the field inputs to ensure that no damage is done to the system as result of high voltage spikes on the input lines. The commands to circuit breakers, isolators etc. are given by digital output modules.

The on-board relay contacts can carry a maximum of 2 amps current which is sufficient to drive the interposing relays.

The current, voltage, MVA power factor and other analog measurements are done by feeding the signals to the analog input modules. The transducers convert the parameters into acceptable signals in the form 0 -10V, -5 to +5 or 0-20 mA current loop. The input module use ADC having a resolution of 12 bits.

Besides the above technical features, the system bus structure has been specially designed for noisy environment at high data transfer rates.

Some Facts About Tower Wagon

In BEML make Tower Wagons, Transmission is Hydraulic.

In ICF make Tower Wagons, Transmission is Electric.

Fuel in Tower wagon lasts 16 hours average.

Tank Capacity is 650 Litres.

In DETC 4 wheeler Tower Wagon of BHEL there is only one TM.

About SCADA

SCADA is heart of TRD. It monitors and controls system at 220KV/110KV, 25 KV( at TSS, SP and SSP).

Voltage about SCADA :-

24 V DC:- for RTU and Lamps

110 v DC :- control supply of CB

230 V DC :- for panel.

Reactors are used in RVTs.

Tower Wagons:- The grey area of TRD

It is said that TRD has well organised set up. This is half truth only. Most important asset of TRD - the Tower Wagon is grossly neglected. Track machines are also meant for maintaining tracks like the twoer wagons are there for maintaining OHE but while former are taken care by huge organisational back upsuch as ZMC and TMC, tower wagons are left at God's mercy.
Not only the maintenance of Tower wagons is haywire, they are allowed to be misused:-
1.Used for trailing window inspections
2.Used for carrying material
3.Used for hauling empty wagons.

It becomes risky to move 4 wheelers as they may stall on line, and 8 wheelers are always having some major problem in one of their engines. What is the solution?
In my opinion the only solution is that old meter guage or narrow guage sheds which are being closed or are being reopened on flimsy ground be converted into exclusive Tower Wagon maintenance sheds.