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

) Notch to notch relay Q52 must not be energized
c) The valve ZSMGR must be at normal position.
5.7.2.2 In case of auto regression of the tap changer GR the relay Q50 is de-energized. The
'down' valve SMGR-VE2 is energized directly by passing BL and MP interlocks.
5.7.2.3 Auto regression also takes place in the event of wheel slipping, the action takes place
via line 700 and the closed contact of relay Q48. Relay Q48, is energized in the event of wheel
slipping through relay QD. In such case slip protection relay Q51 is energized temporarily and
gives supply to down valve SMGR-VE2 till the relay Q48 drops through relay QD after the arrest of
wheel slip.
5.7.2.4 A down movement of the tap changer is interrupted automatically on reaching position
“0” by interruption of the feed supply.
5.7.2.5 The relay Q46 supervises the continued running of the air motor during regression with
MP on position “0” and thus the return of the tap changer to zero.
The following conditions must be satisfied for proper functioning of the relays
a) The running braking drum MP must be at position "0"
b) The tap changer must be on position other than zero
c) The handle of the valve ZSMGR on the pneumatic control panel must be at the
normal operating position.
Should an air motor stop running with the tap changer away from the zero position and
MP on position “0”, the relay Q46 remains energized and causes the relay Ql18 drop out and open
DJ after 5 seconds,
Any down or up movement of the tap changer can be stopped at any time by returning
the master controller to position "N". The tap changer then remains at whatever position has been
reached.
5.7.3 CONTROL BY MASTER CONTROLLER – IMPULSE (+) OR (-)
(Ref. fig. 5.7.2)
The switch positions (+) or (-) are intended for notch by notch up or down movement of
the tap changer both for running and for braking operation.
The switching sequences and inter relationship correspond to those described under
5.7.2. In addition, the notch to notch relay Q52 goes into action, the feed lines 079 is energized at
position (+) or (-).
At all positions for up or down movement either the up or the down valve is energized.
This energizing will be interrupted by contacts of the relay Q52 as soon as the air motor starts
running. The relay Q52, is energized between notches via the contacts 7-8 ASMGR, this state
being maintained via the self holding contacts in the line 079-087. The self holding circuit of Q52 is
not cancelled until the master controller handle has been returned to position "N". This
arrangement ensures that the tap changer always moves by only one notch at a time. The
completion of the notch to notch movement is assured by the pneumatic control system.