remote control equipment - Indian Railways Institute of Electrical ...
remote control equipment - Indian Railways Institute of Electrical ...
remote control equipment - Indian Railways Institute of Electrical ...
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7.3 SCADA EQUIPMENT<br />
7.3.1 General<br />
The SCADA <strong>equipment</strong> at the RCC is called Master Station while that <strong>of</strong> the <strong>control</strong>led<br />
station is referred to as Remote Terminal Unit (RTU).<br />
7.3.2 Transmission Path<br />
Underground telecommunication trunk cable is provided for transmitting the signals from<br />
and to the RCC and the <strong>control</strong>led Remote Terminla Units (RTU). Three pairs <strong>of</strong> conductors<br />
(One pair for “Send”, one pair for “receive” and the third as spare) from this cables are made<br />
available for <strong>remote</strong> <strong>control</strong> operation. These days optical fibre cables are used in most <strong>of</strong> the<br />
divisions instead <strong>of</strong> above mentioned copper cables. Sometimes, microwave communications is<br />
used.<br />
7.3.3 Isolating Transformers<br />
To limit the build up <strong>of</strong> longitudinal induced voltage on account <strong>of</strong> induction effects <strong>of</strong> 25<br />
kV traction, isolating transformers are provided on the cable circuit at intervals <strong>of</strong> 10 to 15 km.<br />
The cable is tapped at the RCC and each <strong>control</strong>led station and 3 pairs <strong>of</strong> conductors are<br />
terminated on a terminal board. Isolating transformer <strong>of</strong> impedance ratio 1120 : 1120 is<br />
provided at the point <strong>of</strong> tapping.<br />
7.3.4 Repeater Stations<br />
Voice frequency repeaters are provided at intervals <strong>of</strong> 40 50 km to boost the signal and make<br />
good the been attenuation. The amplifier gain at the repeater station is about 20 dB. with an<br />
equilser incorporated to compensate upto 0.02 dB/kHz/km Depending upon the distance the<br />
repeater gain is state that the signal level at any point enroute is within cenrtain prescribed limits.<br />
It the lead is long suitable surge arrestors are provided inside the <strong>equipment</strong> room to ---- the ----<br />
. The metalic sheath <strong>of</strong> the lead in cable shall also be kept insulated from the earth system <strong>of</strong> the<br />
switching station to prevent induction effect. the insulated conductor alone being led into <strong>control</strong><br />
panels for the same reason switching station earthing. LT 240 V auxihary transformer neutral<br />
earthing and earth <strong>of</strong> R C <strong>equipment</strong> are all kept separate and distinct and are NOT<br />
interconnected In addition the switching station structure should be solidiy bonded to the track<br />
rails by two independent connections.<br />
7.3.5 Microwave Communication<br />
In some <strong>of</strong> the sections on <strong>Indian</strong> <strong>Railways</strong> didicated Microwave channel at carner frequency <strong>of</strong> 18<br />
GHz has been provided for the purpose <strong>of</strong> communication.<br />
7.3.6 Optical Fibre Cable<br />
Optical fibre cable has also been introduced for communication in some sections <strong>of</strong> <strong>Indian</strong><br />
<strong>Railways</strong> which is also used for RC <strong>equipment</strong><br />
Details <strong>of</strong> the interface between the latest communication systems and the RCC/RTU <strong>equipment</strong><br />
may be seen in the relevant technical documents.<br />
7.3.7 Master Station Equipment<br />
Hardware Configuration: Dual main micro-computer/mini-computer system. one main and the other<br />
hot standby. is provided at the master-station. each system interfaces whtih its front end<br />
processors. If any. and modem for communication with RTUs and with the man-machine interface<br />
<strong>equipment</strong> to provied up-to-date network data and to accept commands. Each system has its own<br />
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