GE 750, Instruction Manual, Page: 247 / 504

GE Power Management 750/760 Feeder Management Relay 13-
31
13 S6 MONITORING 13.8 EQUIPMENT
13
13.8.3 ARCING CURRENT
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 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.
Figure 13–16: ARCING CURRENT MEASUREMENT
■
ARCING CURRENT
■
[ENTER] for more
The
ARCING CURRENT
setpoints path is:
\ SETPOINTS \ S6 MONITORING \ EQUIPMENT \ ARCING CURRENT
TOTAL ARCING CURRENT
FUNCTION: Disabled
Range: Disabled, Alarm, Latched Alarm, Control
Select the required function. Note that the total arcing current for each phase
will still be available for display under
A3 MAINTENANCE \ ARCING CURRENT
if set
to Disabled .
TOTAL ARCING CURRENT
RELAYS (3-7): -----
Range: Any Combination of the 3-7 AUXILIARY Relays
Select the output relays required.
TOTAL ARCING CURRENT
START DELAY: 32 ms
Range: 0 to 100 in steps of 1 ms
Enter the expected ms time 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.
TOTAL ARCING CURRENT
LIMIT: 1000 kA
2
-cyc
Range: 1 to 50000 in steps of 1
Enter the total arcing current in kA
2
–cycle, at which this feature is to cause an
alarm. For example, if an alarm is desired as soon as the total arcing current in
any phase exceeds 1000 kA
2
–cycle, enter
1000
for this setpoint. An output will
occur when the total arcing current in any phase reaches this setting.
SR750
Trip
Command
Breaker
Contacts
Part
Arc
Extinguished
100 ms
Programmable
Start Delay
Start
Integration
Stop
Integration
Total Area =
Breaker
Arcing
Current
(kA·cycle)
ARCING.CDR