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CHAPTER 5: SETTINGS
5.7
S6 Current Elements
5.7.1
Short Circuit Trip
SHORT
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
PATH: SETTINGS
S6 CURRENT ELEM.
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Care must be taken when turning On this feature. If the interrupting device (contactor
or circuit breaker) is not rated to break the fault current, this feature should be
disabled. Alternatively, this feature may be assigned to an auxiliary relay and
connected such that it trips an upstream device that is capable of breaking the fault
current.
If turned on, the Short Circuit element functions as follows.
A trip occurs once the magnitude of either Ia, Ib, or Ic exceeds the Pickup Level × Phase CT
Primary for the time specified by
also be enabled. The
SHORT CIRCUIT TRIP BACKUP DELAY
INTENTIONAL S/C TRIP DELAY
is "On" and a Short Circuit trip has initiated, a second trip occurs if the motor phase
BACKUP
current persists for a time exceeding the
that this second trip be assigned to 2 Auxiliary or 3 Auxiliary which would be dedicated as
an upstream breaker trip relay. Whenever the output relay assigned to backup trip
operates, it will remain latched regardless of how the trip relay is configured for the Short
Circuit Trip element.
Various situations (e.g. charging a long line to the motor or power factor correction
capacitors) may cause transient inrush currents during motor starting that may exceed
the
SHORT CIRCUIT TRIP PICKUP
is adjustable in 10 ms increments. This delay can be fine tuned to an
TRIP DELAY
application so it still responds very fast but rides through normal operational disturbances.
Normally, the
INTENTIONAL S/C TRIP DELAY
SHORT CIRCUIT TRIP
SHORT CIRCUIT
TRIP: Off
SHORT CIRCUIT
TRIP
ASSIGN TRIP
RELAYS:
SHORT CIRCUIT
TRIP
INTENTIONAL S/C
TRIP
SHORT CIRCUIT
TRIP
ASSIGN BACKUP
RELAYS:
SHORT CIRCUIT
TRIP
INTENTIONAL S/C TRIP DELAY
plus the breaker clearing time. If the
SHORT CIRCUIT TRIP BACKUP DELAY
level for a very short period of time. The
is set as quick as possible, 0 ms. This time may
Range: Off, Latched, Unlatched
Range: On, Off
Range: Tri, Trip & Aux 2, Trip & Aux2 &
Aux3, Trip & Aux3, Aux2, Aux2
& Aux3, Aux3
Range: 2.0 to 20.0 x CT in steps of 0.1
Range: 0 to 1000 ms in steps of 10
Range: On, Off
Range: Auxiliary2, Aux2 & Aux3,
Auxiliary3
Range: 10 to 2000 ms in steps of 10
. A backup trip feature may
should be greater than the
SHORT CIRCUIT TRIP
. It is intended
INTENTIONAL S/C
5–59
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