GE T60 Instruction Manual page 413

5 SETTINGS
b) BREAKER ARCING CURRENT

PATH: SETTINGS CONTROL ELEMENTS
 BREAKER 1
 ARCING CURRENT
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
MESSAGE
There is one breaker arcing current element available per CT bank, with a minimum of two elements. This element calcu-
lates 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 com-
pared 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
relays and the breaker mechanism. For maximum measurement accuracy, the interval between change-of-state of the
operand (from 0 to 1) and contact separation should be measured for the specific installation. Integration of the measured
current continues for 100 ms, which is expected to include the total arcing period.
The feature is programmed to perform fault duration calculations. Fault duration is defined as a time between operation of
the disturbance detector occurring before initiation of this feature, and reset of an internal low-set overcurrent function. Cor-
rection is implemented to account for a non-zero reset time of the overcurrent function.
Breaker arcing currents and fault duration values are available under the
 menus.
BREAKER 1(4)
• BKR 1 ARC AMP INT-A(C): Select the same output operands that are configured to operate the output relays used to
trip the breaker. In three-pole tripping applications, the same operand should be configured to initiate arcing current
calculations for poles A, B and C of the breaker. In single-pole tripping applications, per-pole tripping operands should
be configured to initiate the calculations for the poles that are actually tripped.
• BKR 1 ARC AMP DELAY: This setting is used to program the delay interval between the time the tripping sequence is
initiated and the time the breaker contacts are expected to part, starting the integration of the measured current.
• BKR 1 ARC AMP LIMIT: Selects the threshold value above which the output operand is set.
GE Multilin
 
MONITORING ELEMENTS
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-B:
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 ARC AMP BLOCK:
Off
BKR 1 ARC AMP
TARGET: Self-reset
BKR 1 ARC AMP
EVENTS: Disabled
T60 Transformer Protection System
5.7 CONTROL ELEMENTS
BREAKER 1(4) ARCING CURRENT
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: FlexLogic operand
Range: FlexLogic operand
Range: FlexLogic operand
Range: 0.000 to 65.535 s in steps of 0.001
2
Range: 0 to 50000 kA -cycle in steps of 1
Range: FlexLogic operand
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
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ACTUAL VALUES RECORDS
5
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MAINTENANCE
5-277