remote control equipment - Indian Railways Institute of Electrical ...

• Characteristics of the locomotive and speed etc.
• Allowable permissible voltage drop at the farthest end.
• Strength of the system to permit the voltage and current unbalance
caused by the traction single phase loads.
• Suitability of standard equipments.
• The load is within the standard ratings of the transformer and other
equipment under normal and extended feed conditions.
• Availability of reasonably good levelled land as near to Rly track as
possible.
• Location should be away from the dumping yards.
• Location of sub-station should not be less than 3 km from the airport.
• Provision of siding track for loading and unloading of heavy equipments.
• Location should be close to main Rly. station where inspection staff can
reach the spot in the shortest time
4.0.4 On an average the spacing between the successive sub-station as adopted in
earlier electrification schemes was about 50 to 80 km, but with the interlocution of
heavy haul trains and increased passenger and goods traffic the spacing has been
reduced to 40 to 60 km. only. On high density routes it may reduce further by
converting existing SP into TSS and SSP into SP.
4.1 TRACTION POWER SUPPLY SYSTEM
4.1.1 Before going into details of design aspects of various substation
equipments, we may briefly discuss the power supply system adopted for feeding
the traction substations.
4.1.2 Indian Rlys. purchase electric power from various state electricity boards
and as well as from other electric utilities through their regional grids at different
voltage, normally 220/132/110/66 kV. The incoming supply is stepped down to
25 kv. a.c. with the help of step down transformer. The primary winding of the
transformer is connected across two phases of the three phase effectively earthed
system and one terminal of the 25 kV. secondary winding is connected to the
overhead equipment (OHE) and other terminal of the 25 kV. secondary winding is
solidly earthed and connected to the running rails. The load current flows through
the OHE to the locomotive and return through the rails and earth to the traction
sub-station.
The substations are provided as close to the railway traction as possible at
intervals varying from 40 to 60 km depending upon the traffic density and track
conditions. In the initial stages of the AC electrification schemes, traction
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