Tests For Circuit Breaker Failure Protection - Siemens SIPROTEC 7SK80 Manual

3.3.5

Tests for Circuit Breaker Failure Protection

General
If the device provides a breaker failure protection and if this is used, the integration of this protection function
in the system must be tested under practical conditions.
Due to the variety of application options and the available system configurations, it is not possible to make a
detailed description of the necessary tests. It is important to observe local conditions and protection and system
drawings.
Before starting the circuit breaker tests it is recommended to isolate the circuit breaker of the tested feeder at
both ends, i.e. line isolators and busbar isolators should be open so that the breaker can be operated without
risk.
Caution!
Also for tests on the local circuit breaker of the feeder a trip command to the surrounding circuit breakers can
be issued for the busbar.
Non–observance of the following measure can result in minor personal injury or property damage.
Therefore, primarily it is recommended to interrupt the tripping commands to the adjacent (busbar) breakers,
e.g. by interrupting the corresponding pickup voltages.
Before the breaker is finally closed for normal operation, the trip command of the feeder protection routed to
the circuit breaker must be disconnected so that the trip command can only be initiated by the breaker failure
protection.
Although the following lists do not claim to be complete, they may also contain points which are to be ignored
in the current application.
Auxiliary Contacts of the CB
The circuit breaker auxiliary contact(s) form an essential part of the breaker failure protection system in case
they have been connected to the device. Make sure the correct assignment has been checked.
External Initiation Conditions
If the breaker failure protection can be started by external protection devices, the external start conditions must
be checked.
In order for the breaker failure protection to be started, a current must flow at least via the monitored phase.
This may be a secondary injected current.
• Start by trip command of the external protection: binary input functions „>50BF ext SRC" (FNo 1431) (in
spontaneous or fault annunciations).
• After every start, the message „50BF ext Pickup" (FNo 1457) must appear in the spontaneous or fault
annunciations.
• After time expiration TRIP-Timer (address 7005) tripping command of the circuit breaker failure protection.
Switch off test current.
If start is possible without current flow:
• Closing the circuit breaker to be monitored to both sides with the disconnector switches open.
• Start by trip command of the external protection: Binary input functions „>50BF ext SRC" (FNo 1431) (in
spontaneous or fault annunciations).
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A4, Release date 08.2010
Mounting and Commissioning
3.3 Commissioning
321