3 Operation
(continued)
3-156
C232-302-401/402/403/404-603 / C232/EN M/A23
3.25 Tap Changer (Function Group TAPCH)
The transformer tap control function makes it possible to acquire data of one tap position
and to output tap change commands for one tap changer. The functions and settings for
the tap changer are described below.
Acquisition of tap positions
Data on tap positions are acquired in BCD code with 6 bits maximum and one sign bit for
positions in the range of -64 to +63 maximum. The input signals must be connected to
the binary signal inputs in BCD code. The sequence of assignment of binary signal
inputs at TAPCH: Input assign. TapCh 1 defines value in the tap position
signal. The assignment sequence proceeds from the low-value bit to the higher value
bit. Signals are assigned to the sign of the tap position signal by way of configuration
parameter INP: Funct. assignm. V xxx and 'TAPCH: TapChg 1, sign'. If
the 'tap change operating' signal is to be made available for evaluation in order to
suppress the tap position signal while a tap change is in progress, then a binary signal
input must be configured for ”TAPCH: TapCh 1 operating”. Starting and ending
signals will be issued for this input. If there is a logic value of '1' at the input, then a
change in tap position will not be transmitted. The tap position signal is not transmitted
until there is a logic value of '0'. If the unit is configured for suppression of the
intermediate position, then the zero position is not transmitted while a tap change is in
progress.
Control of the tap changer
The transformer tap changer is controlled solely by remote control through the
communication interface via single tap change operations triggered by the tap change
commands HIGHER or LOWER. The effective command range can be set between the
lowest position and the highest position. When the range limits are reached (set value in
lowest or highest tap position), no change commands are issued. If no sign is defined,
then only the positive range is effective, even if the lowest position is set for a negative
value. If only a positive range is set, then a configured sign will not be effective. The
operating mode for the change command can be set for time control, long command, or
short command. As soon as the tap change command is issued, the output relay
configured for the tap changer is triggered 'higher' or 'lower' for the set time period.
When command blocking is activated, the tap change command will be rejected at the
communication interface. Command initiation is possible in both the 'remote' and 'local'
states.
Note
Once the operating time monitoring period has elapsed, the current tap position will not
be transmitted. Tap changer operation cannot be triggered by programmable logic.
Output relays can be directly triggered by the control system. In this case, however,
sequence control is handled by the control system itself.
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