Mounting and Commissioning
3.2 Checking Connections
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
399
Voltage Transformer-Protective Switch
Since it is very important for the undervoltage protection, impedance protection and voltage-dependent definite
time and inverse time overcurrent protection that these functions are blocked automatically if the circuit breaker
for the voltage transformers has tripped, the blocking should be checked along with the voltage circuits. Switch
off the voltage transformer protection switches.
One should check in the operational annunciations that the VT mcb trip was detected (annunciation
„>FAIL:Feeder VT“ „ON“). A requirement for this is that the auxiliary contact of the VT mcb is connected
and correspondingly allocated.
Close the VT mcb again: The above annunciations appear under the „going“ operational annunciations, i.e.
with the comment „OFF“ (e.g. „>FAIL:Feeder VT“ „OFF“).
Note
The definite time overcurrent with undervoltage seal-in blocking must be realised with the binary input
„>Useal-inBLK“ (1950)
If one of the indications does not appear, check the connection and allocation of these signals.
If the „ON“ and „OFF“ messages are exchanged, then the breaker auxiliary contact type should be checked
and corrected if necessary.
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