Manual
KVCG202/EN M/H
Figure 31: Connection of 40 tap potential divider to KVGC with VT voltage input
4.9.1 Tap changer maintenance
4.9.1.1 Tap change operations counter
The relay provides an indication of the maximum number of tap changer operations. The
user may configure the logic to initiate an alarm through the relay masks if the number of
tap change operations has exceeded a preset value. If Link [LOG4] is set to ‘1’, the tap
change operation will be blocked and hence put the relay out of service when the counter
threshold is exceeded.
The “Tap Change Operations Counter” is incremented by 1 each time the tap position is
changed. A tap change may be initiated by the internal tap change control functions,
manual tap change, local control sequences or remote tap change sequences.
If the auxiliary power is lost the operation counter values and TPI are retained. On power
restoration the tap difference between the TPI on power off and power on is incremented
to the operations counter.
4.9.1.2 Frequent operations monitor
An alarm is initiated if the number of tap change operations exceeds a certain threshold
over a preset time period (tP). The ‘FreqOps’ output relay allocated in the Relay Mask
picks up to give the alarm condition. If Logic Link [LOG5] is set to ‘1’ and the relay is set
in ‘AUTO’ mode, -any further tap change operations are blocked and hence put the relay
out of service until the alarm condition is cleared. An event is raised and the number of
operations is recorded after every elapsed time period tP. The delay timer and the
counter for the tap change operation is reset after the event is logged.
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