Autoreclose Implementation - GE P4A Technical Manual

P54A/B/C/E
3

AUTORECLOSE IMPLEMENTATION

Before describing this function it is first necessary to understand the following terminology:
A Shot is an attempt to close a circuit breaker using the Autoreclose function.
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Multi-shot is where more than one Shot is attempted.
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● Single-shot is where only one Shot is attempted.
Dead Time denotes the time between initiation of the Autoreclose operation and the attempt to close the
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circuit breaker.
Reclaim time is the time following the initiation of the circuit breaker closing and the resetting of the
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Autoreclose scheme should the Autoreclose attempt be successful and the protection does not detect a
subsequent fault condition.
High-speed Autoreclose is generally regarded as an Autoreclose application where the Dead Time is less
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than 1 second.
Delayed Autoreclose is generally regarded as an Autoreclose application where the Dead Time is greater
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than 1 second.
This product features a multiple-shot Autoreclose function, which is suitable for both High-speed Autoreclose and
Delayed Autoreclose.
The Autoreclose function can be set to perform a single-shot, two-shot, three-shot or four-shot cycle. Dead Times
for all shots can be adjusted independently.
If a circuit breaker closes successfully at the end of the Dead Time, a Reclaim Time starts. If the circuit breaker
does not trip again, the Autoreclose function resets at the end of the Reclaim Time. If the protection trips again
during the Reclaim Time, the sequence advances to the next shot in the programmed cycle. If all programmed
reclose attempts have been made and the circuit breaker does not remain closed, the Autoreclose function goes
into Lockout, whereupon manual intervention is required.
An Autoreclose cycle can be initiated by operation of an internal or external protection element provided it is
mapped correctly, and that the circuit breaker is closed when the protection operates.
You can choose to initiate the Dead Time on:
Protection operation
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A protection reset
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A Line Dead condition
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Circuit breaker operation
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At the end of the relevant Dead Time, provided system conditions are suitable, a circuit breaker close signal is
given. The system conditions to be met for closing are that:
the system voltages are in synchronism
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or that the dead line/live bus or live line/dead bus conditions exist as indicated by the internal system check
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synchronising element
and that the circuit breaker closing spring, or other energy source, is fully charged as indicated by the circuit
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breaker healthy input.
The circuit breaker close signal is removed when the circuit breaker closes.
If the protection trips and the circuit breaker opens during the Reclaim Time, the Autoreclose function either
advances to the next shot in the programmed cycle, or if all programmed reclose attempts have been made, goes
into Lockout. Each time a closure is attempted, a sequence counter is incremented by 1 and the Reclaim Time
starts again.
Autoreclose is configured in the AUTORECLOSE column of the relevant settings group. The function is disabled by
default. If you wish to use it you must enable it first in the CONFIGURATION column.
P54xMED-TM-EN-1
Chapter 7 - Autoreclose
127