GE L90 Instruction Manual page 518

CONTROL ELEMENTS
5.8.11.2 Breaker arcing current
SETTINGS  CONTROL ELEMENTS  MONITORING ELEMENTS  BREAKER 1(4) ARCING CURRENT
 BREAKER 1
 ARCING CURRENT
5
There is one breaker arcing current element available per CT bank, with a minimum of two elements. This element
calculates an estimate of the per-phase wear on the breaker contacts by measuring and integrating the current squared
passing through the breaker contacts as an arc. These per-phase values are added to accumulated totals for each phase
and compared to a programmed threshold value. When the threshold is exceeded in any phase, the relay can set an
output operand to "1." The accumulated value for each phase can be displayed as an actual value.
The operation of the scheme is shown in the following logic diagram. The same output operand that is selected to operate
the output relay used to trip the breaker, indicating a tripping sequence has begun, is used to initiate this feature. A time
delay is introduced between initiation and the starting of integration to prevent integration of current flow through the
breaker before the contacts have parted. This interval includes the operating time of the output relay, any other auxiliary
5-332
 CT FAILURE

 DETECTOR 4
 VT FUSE FAILURE 1



 VT FUSE FAILURE 4


 OPEN POLE


 THERMAL OVERLOAD

 PROTECTION
 BROKEN CONDUCTOR


BKR 1 ARC AMP

FUNCTION: Disabled
BKR 1 ARC AMP

SOURCE: SRC 1
BKR 1 ARC AMP INT-A:

Off

BKR 1 ARC AMP INT-C:

Off
BKR 1 ARC AMP

DELAY: 0.000 s
BKR 1 ARC AMP LIMIT:

1000 kA2-cyc
BKR 1 INTERRUPTION

RATING: 31.5 kA
BKR 1 CLR ARC AMPS:

Off
BKR 1 ARC AMP BLOCK:

Off
BKR 1 ARC AMP

TARGET: Self-reset
BKR 1 ARC AMP

EVENTS: Disabled
See page 5-345
See page 5-346
See page 5-349
See page 5-352
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4
Range: FlexLogic operand
Range: FlexLogic operand
Range: 0.000 to 65.535 s in steps of 0.001
Range: 0 to 50000 kA
Range: 0.0 to 100.0 kA in steps of 0.1
Range: FlexLogic operand
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
2
-cycle in steps of 1