Description of Operation
GARD 8000 Distance Relay
RFL Electronics Inc.
9.24
BREAKER SUPERVISION FUNCTIONS
The GARD 8000 provides two functions useful for indicating need for breaker maintenance; total
accumulated breaking current and excessive number of trips.
9.24.1
ACCUMULATED BREAKING CURRENT
The GARD 8000 provides breaker supervision by calculating the square of the breaking current. The
kA
2
of the current is proportional to the actual energy opened by the breaker.
The ‘breaker opening current’ is measured as the square of the maximum current between the time of
the trip (or manual open command) and the time the breaker opens.
There are two settings for this function:
•
Alarm level for accumulated kA
2
•
Actual kA
2
The second setting is used to enter a ‘starting value’ for the calculated sum in case the breaker has been
in service some time after maintenance before GARD 8000 is installed. It is also used to reset the sum
following breaker maintenance.
9.24.2
EXCESSIVE NUMBER OF TRIPS
The function for excessive number of trips limits the possibility of uncontrolled open and close
operations of the breaker. The number of trips can be set to 1 - 40, and when the set number is
exceeded during a 30 minute time period, further reclosing of the breaker is prevented by asserting the
lock-out function in the recloser.
9.24.3
ARC DETECTOR
This function detects an arc over an open breaker pole. When the breaker opens (as indicated by the
52b contact) and the current is above the set level for ‘Arc detector pick up’, the signal ‘Arc detector
trip’ will be generated after the set time delay ‘Arc detector time’.
August 1, 2009
9-84
973.334.3100
