Protection General - Siemens SIPROTEC 7SS523 V3.2 Manual

5.9

Protection General

5.9.1 Current-Controlled TRIP Reset
Minimum duration
of TRIP command
5.9.2 Local Control of the Bay Unit
This section summarizes general information required by the SIPROTEC 7SS52 V4
distributed busbar and breaker failure protection.
For a reset of the TRIP command, it must be ensured that the tripped circuit breaker
has actually been opened and that the trip circuit of the bay unit has been interrupted
by the circuit breaker auxiliary contact.
If the trip relay interrupts the tripping current prematurely, its contacts are overloaded
and destroyed.
A TRIP command from the busbar protection is only transmitted to the circuit breaker
of the faulted feeder if the feeder current exceeds the current threshold for TRIP re-
lease I>TRIP (XX13/CU).
The relays for the TRIP command and the transfer trip command are reset if after the
time Tmin TRIP (6106/CU) the feeder current drops below the threshold
I> BF (XX18/CU) or I> BF-EF (XX19/CU).
Figure 5-39 Minimum duration of TRIP command
If you want to ensure that the operating status of the bay units set with the parameter
Bay status (XX12/CU) and the function keys F1 and F3 cannot be changed in the
bay units, you can block the local control of the bay units with the parameter CTRL
REL BU (6318/CU).
7SS52 V4 Manual
C53000-G1176-C182-1
Protection General
165