3.2 Checking Connections
261
7UM61 Manual
C53000-G1176-C127-3
• Check control circuits from the output relays via control lines to the circuit breakers
and isolators etc.
• Check binary input signals via signal lines up to the protection device by activating
the external contacts.
Protective Switch-
es for the Voltage
Transformers
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
voltage transformer protection switches.
Check in the operational messages that the VT mcb trip was entered (indication
“>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 indications appear under the "going" operational
indications, i.e. with the comment "OFF“ (e.g.
“>FAIL:Feeder VT”
“OFF”).
Note
The definite time overcurrent with undervoltage seal-in blocking must be realized with
the input
“>Useal-in BLK”
(FNo. 1950).
If one of the indications does not appear, check the connection and allocation of these
signals.
If the "ON" comment and "OFF" comment are interchanged, the contact type (normally
closed or normally opened) must be checked and corrected.
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