Reclaim Timer Setting - GE MiCOM P40 Agile Technical Manual

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P14x
1st dead time = 5 - 10 seconds
2nd dead time = 30 seconds
3rd dead time = 60 - 180 seconds
4th dead time = 1 - 30 minutes
8.3

RECLAIM TIMER SETTING

A number of factors influence the choice of the reclaim timer:
Supply continuity: Large reclaim times can result in unnecessary lockout for transient faults.
Fault incidence/Past experience: Small reclaim times may be required where there is a high incidence of
lightning strikes to prevent unnecessary lockout for transient faults.
Spring charging time: For HSAR the reclaim time may be set longer than the spring charging time to ensure
there is sufficient energy in the circuit breaker to perform a trip-close-trip cycle. For delayed Autoreclose
there is no need as the dead time can be extended by an extra CB healthy check window time if there is
insufficient energy in the CB. If there is insufficient energy after the check window time the IED will lockout.
Switchgear maintenance: Excessive operation resulting from short reclaim times can mean shorter
maintenance periods. A minimum reclaim time of more than 5 seconds may be needed to allow the circuit
breaker time to recover after a trip and close before it can perform another trip-close-trip cycle. This time
will depend on the circuit breaker's duty rating.
The reclaim time must be long enough to allow any time-delayed protection initiating Autoreclose to operate.
Failure to do so would result in premature resetting of the Autoreclose scheme and re-enabling of instantaneous
protection. If this condition arose, a permanent fault would effectively look like a number of transient faults,
resulting in continuous autoreclosing, unless additional measures are taken such as excessive fault frequency
lockout protection.
Sensitive earth fault protection is applied to detect high resistance earth faults and usually has a long time delay,
typically 10 - 15 seconds. This longer time may have to be taken into consideration, if autoreclosing from SEF
protection. High resistance earth faults are rarely transient and may be a danger to the public. It is therefore
common practise to block Autoreclose by operation of sensitive earth fault protection and lockout the circuit
breaker.
A typical 11/33 kV reclaim time is 5 - 10 seconds. This prevents unnecessary lockout during thunderstorms.
However, reclaim times of up to 60 - 180 seconds may be used elsewhere in the world.
P14xEd1-TM-EN-1
Chapter 13 - Autoreclose
307

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