9 Visualization
Maschinenfabrik Reinhausen GmbH 2020308 6385142/08 ENETOS
®
ED
9.32.4 Tap-change supervisory control
The tap-change supervisory control monitors both the drive shaft between
on-load tap-changer(s) and motor-drive unit and the correct switching of the
diverter switch. The tap-change supervisory control is also performed when
the motor-drive unit is actuated using the hand crank.
If the on-load tap-changer is equipped with tap-change supervisory control,
then the monitoring system uses the status of the monitoring contacts S80
and S81 for the following evaluations:
▪ If both monitoring contacts report "OFF" (there is no signal) and no tap-
change operation is being performed at that time, then the monitoring sys-
tem triggers the event Both tap-change supervisory control contacts OFF.
▪ If both monitoring contacts report "ON" (there is a signal) and no tap-
change operation is being performed at that time, then the monitoring sys-
tem triggers the event Both tap-change supervisory control contacts ON.
▪ If a tap-change operation is performed and no change in the signals on
the monitoring contacts occurs (e.g. from 1 to 2), then the monitoring sys-
tem triggers the event Tap-change operation without diverter switch oper-
ation.
▪ Checking whether the tap-change supervisory control is correctly con-
nected and the position sensor is correctly calibrated. If not, the monitor-
ing system triggers the event Tap-change supervisory control wiring error.
▪ If the signal of a monitoring contact changes from "ON" to "OFF" during a
tap-change operation, then this position is marked in the torque curve with
a vertical line. This indicates that a diverter switch action has occurred.
▪ Monitoring the diverter switch action. If the diverter switch action does not
occur at the right time, then the monitoring system triggers the event mes-
sage OLTC and MD insufficiently centered.
▪ For on-load tap-changer sets or on-load tap-changer combinations (multi-
column versions), the monitoring system monitors synchronous switching
of the on-load tap-changers. If synchronization is not sufficient, then the
monitoring system triggers the event OLTC synchronization insufficient.
9.32.5 Evaluated and unevaluated tap-change operations
The monitoring system distinguishes between evaluated and unevaluated
tap-change operations. A tap-change operation is considered to have been
evaluated if a diverter switch action is detected and it was possible for the
torque limits to be checked. The M1...M8 >/>> torque limits are not checked
during an unevaluated tap-change operation.
The entire torque curve is stored in the database, both for evaluated as well
as unevaluated tap-change operations.
A tap-change operation is not evaluated in the following cases:
▪ The motor voltage, motor current or motor frequency are outside of the
permissible range.
▪ The recorded temperatures are outside of the permissible range.
▪ Faulty rotary encoder signal.
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