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7SR11 & 7SR12 Description Of Operation

The dead time is initiated when the trip output contact reset, the pickup is reset and the CB is open.

The CB close output relay is energised after the dead time has elapsed.

Figure 4-1 Typical AR Sequence with 3 Inst and 1 Delayed trip

4.1.3 AUTORECLOSE PROT’N MENU

This menu presents the Overcurrent Protection elements available for each type of Fault i.e. P/F, E/F (N/G) or

SEF and allows the user to select those that are to be applied as Inst trips; those that are to be applied as

Delayed Trips; and those that are to be applied as HS Trips (HighSet), as required by the selected sequence.

There is no corresponding setting for External as the External protection type is not normally controlled by the

Auto Reclose Relay. The resultant configuration enables the Auto Reclose function to correctly apply the required

Protection for each shot in a sequence.

4.1.4 AUTORECLOSE CONFIG MENU

This menu allows the following settings to be made:-

79 Autoreclose Enabled turns ON all AutoReclose Functions.

79 Num Shots Sets the allowed number of AutoReclose attempts in a sequence.

79 Retry Enable Enabled configures the relay to perform further attempts to automatically Close the

Circuit Breaker where the CB has initially failed to close in response to a Close

command. If the first attempt fails the relay will wait for the 79 Retry Interval to expire

then attempt to Close the CB again.

79 Retry Attempts Sets the maximum number of retry attempts.

79 Retry Interval Sets the time delay between retry attempts.

79 Reclose Blocked

Delay If the CB is not ready to receive a Close command or if system conditions are such

that the CB should not be closed immediately e.g. a close-spring is not charged, then

a Binary input mapped to Reclose Block can be raised and the Close pulse will not be

issued but will be held-back. The 79 Reclose Blocked Delay sets the time Reclose

Block is allowed to be raised, if this time delay expires the Relay will go to Lockout. If

Reclose Block is cleared, before this time expires, then the CB Close pulse will be

issued at that point in time. Dead Time + Reclose Blocked Delay = Lockout.

79 Sequence Fail Timer Sets the time that AutoReclose start can be primed. Where this time expires before all

the DAR start signals are not received i.e. the CB has opened, protection pickups have

reset and the trip relay has reset, the Relay goes to Lockout.

Siemens 7SR12 Argus User Manual

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