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

elay Q48. If the wheels on one bogie start slipping, the current on the motor concerned drops,
This is detected by the relay QD1 or QD2 which, on operation energize the relay Q48 via its
normally open contacts. (Ref.fig. 5.7.1).
The relay Q48 can be energized only if the traction braking switched CTF1-2 are at
position "Running".
The auxiliary contacts of the relay Q48 are provided with a drop out delay of 5
secs., which will begin as soon as the relay has been de-energized. This means that sanding will
continues for 5 secs, after wheel slip has ceased (relay QD has dropped out).
Operation of relay Q48 as a result of wheel slip and operation of relay QD1 or QD2, also
results in automatic regression of the tap changer (GR) till the relay QD1 or QD2 drops out due to
arrest of the wheel slip.
With multiple unit operation the solenoid valves VESA of the trailing locomotives are
controlled from the leading locomotives.
By operation of the pedal PSA on the leading locomotives the appropriate solenoid valve
VESA on all trailing locomotives is energized.
Upon operation of the differential relay QD, the relay Q48, of any locomotive is
energized and not only the solenoid valve VESA of the locomotive concerned, but the
corresponding solenoid valves VESA of all locomotives are energized thereby sanding occurs
ahead of all driven axles.
5.9 LIGHTS, FANS & SIGNALING CIRCUIT
5.9.1 GENERAL (Ref. fig. 5.9.1)
Signaling and lighting circuits are connected to the 110 V dc supply.
The auxiliary contacts of the BL switch box should be closed by inserting the key in the
switch box of any one cab for energizing the signaling circuits. Lighting circuits are energized
independent of BL switch.
With multiple unit operation the signaling circuits in the trailing locomotives are supplied
with power through the MU couplers from the leading locomotive.
5.9.1.1 SIGNALING CIRCUITS
The signaling circuits are protected by fuse CCLS.
With the high voltage circuit breaker DJ open and the tap changer GR at position '0', all
signaling lamps, except the lamp LSOL, LSP, LSBCR and LSRSI must light up when the battery
switch HBA closed. This acts as a check whether any lamp is defective. For checking the signal
lamps LSP and LSRSI push button switch BPT is used. As soon as the high voltage circuit breaker
DJ is closed all signaling lamps, except the lamp LSGR, must go out. The lamp LSGR goes out
when the tap changer GR has left position ‘0'.