Traction Rolling Stock - Indian Railways Institute of Electrical ...

The fan draws the air through the cooling ducts inside the rectifier cubicle. The exhaust
air is forced into the underfloor space of the locomotive.
The rectifier unit has been provided with fuses for protection against over loads. Suitable
signaling and rectifier cubicle fuses are provided to give failure indication both at the driver's Desk.
A damping system comprising of capacitors and resistors is installed on the dc side of
for each bridge. The D.C. damping system is arranged next to the fan on the right side of the
cubicle towards the aisle of locomotive.
1.4.3 Connection:
Each cubicle contains a Greatz bridge connection ; each of 4 arms consists of 4 cells
connected in parallel and 3 cells connected in series in case of AEG/NGEF/Ruttonsha make and 4
cells in parallel and 4 cells in series in HIRECT Type.
1.4.4 Emergency Operation
In order to permit emergency operation upon failure of one or more blowers, a bridging
or changeover switch HVSI is fitted in each cubicle which permits the following types of operation:
0 -- Motors and relay switched off.
I -- Motors and relay in operation,
II -- Motors switched off, relay in operation.
III -- Motors switched on, relay in operative.
The following operating procedures are possible for emergency operation :
At position II - One rectifier cubicle is out of operation, the supervision of the second
cubicle is switched on. The supervision of the faulty cubicle is switched on for test purpose.
At position III - Upon failure of a blower motor this can be switched off alone via the
switch DMVSI. The second blower can continue to be operated. The blower supervision of this
cubicle is then inoperative. However, the second cubicle can be operated at full power.
The switch HVSI has the following additional functions :
and L2.
At position 0 and II - De-energizing the relay Ql18 and switching off the line contactors LI
The position 0 it is thus possible to disconnect one rectifier completely while the
supervision of the second rectifier remains in operation.
At position 0 the rectifier cubicles may be tested.
1.4.5 Protective devices
Protection against hole storage effect :- An assembly consisting of a capacitor and a resistor
connected in parallel across each cell.
This arrangement prevents dangerous over voltages across the cells which occur upon
cutoff of the upon commutation.
At the same time, these RC-elements also damp dangerous over-voltage which may be
transmitted to the rectifier via the transformer, should surges occur in the catenary.