GE 750 Instruction Manual page 241

CHAPTER 5: SETPOINTS
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ARCING CURRENT
750 FEEDER MANAGEMENT RELAY – INSTRUCTION MANUAL
FIGURE 5–50: Trip Counter Logic
Arcing Current
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PATH: SETPOINTS S6 MONITORING
[]
MESSAGE
MESSAGE
MESSAGE
The relay calculates an estimate of the per-phase wear on the breaker contacts by
measuring and integrating the arcing current squared passing through the contacts while
they are opening. These per-phase values are added to accumulated totals for each phase
and compared to a programmed threshold value. When the threshold is met or exceeded
in any phase, the relay can be used to generate an alarm. The threshold value can be set to
a maintenance specification provided by the breaker manufacturer.
For the
TOTAL ARCING CURRENT START DELAY
from the moment a trip command is issued, until the breaker contacts will actually begin to
open. This setpoint is used by the relay to determine when to start integrating. The
integration continues for 100 ms, by which time most modern breakers will have cleared a
fault.
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EQUIPMENT
ARCING CURRENT
FUNCTION: Disabled
ARCING CURRENT
RELAYS (3-7): -----
ARCING CURRENT
START DELAY: 32 ms
TOTAL ARCING CURRENT
LIMIT: 1000 kA2-cyc
setpoint, enter the expected ms time delay,
S6 MONITORING
ARCING CURRENT
Range: Disabled, Alarm,
Latched Alarm,
Range: Any combination of 3
to 7 Auxiliary relays
Range: 0 to 100 ms in steps
of 1
2
Range: 1 to 50000 kA
steps of 1
-cyc in
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