Manual Cb Control; Circuit Breaker (Cb) - Siemens 7SR11 Manual

4.2

Manual CB Control

A Manual Close Command can be initiated in one of three ways: via a Close CB binary input, via the data
communication Channel(s) or from the relay CONTROL MODE menu. It causes an instantaneous operation via
79MC Close CB binary output, over-riding any DAR sequence in progress.
Repeated Manual Closes are avoided by checking for Positive edge triggers. Even if the Manual Close input is
constantly energised the relay will only attempt one close.
A Manual Close will initiate Line Check if enabled. If a fault appears on the line during the Close Pulse or during
the Reclaim Time with Line Check enabled, the relay will initiate a Trip and Lockout. This prevents a CB being
repeatedly closed onto a faulted line. Where Line Check = DELAYED then instantaneous protection is inhibited
until the reclaim time has elapsed.
Manual Close resets Lockout, if the conditions that set Lockout have reset i.e. there is no trip or Lockout input
present.
Manual Close cannot proceed if there is a Lockout input present.
With the Autoreclose function set to Disabled the Manual Close control is still active.
CB Controls Latched
CB controls for manually closing and tripping can be latched for extra security.
With Reset operation, the control resets when the binary input drops off. This can lead to multiple control restarts
due to bounce on the binary input signal.
With Latch operation, the close or trip sequence always continues to completion (or sequence failure) and bounce
on the binary input is ignored.
Reset operation can be useful, however, as it allows a close or trip sequence to be aborted by dropping off the
binary input signal.
Close CB Delay
The Close CB Delay is applicable to manual CB close commands received through a Close CB binary input or
via the Control Menu. Operation of the 79 MC Close CB binary output is delayed by the Close CB Delay setting.
The status of this delay is displayed on the relay fascia as it decrements towards zero. Only when the delay
reaches zero will the close command be issued and related functionality initiated.
Blocked Close Delay
The close command may be delayed by a Block Close CB signal applied to a binary input. This causes the
feature to pause before it issues the CB close command and can be used, for example, to delay CB closure until
the CB energy has reached an acceptable level. If the Block signal has not been removed before the end of the
defined time, Blocked Close Delay, the relay will go to the lockout state.
Open CB Delay
The Open CB Delay setting is applicable to CB trip commands received through an Open CB binary input or via
the Control Menu. Operation of the Open CB binary output is delayed by the Open CB Delay setting. The status
of this delay is displayed on the relay fascia as it decrements towards zero. Only when the delay reaches zero will
the trip command be issued and related functionality initiated.
It should be noted that a CB trip initiated by an Open CB command is fundamentally different from a CB trip
initiated by a protection function. A CB trip caused by a CB Open command will not initiate functionality such as
circuit-breaker fail, fault data storage, I
4.3

Circuit Breaker (CB)

This menu includes relay settings applicable to both manual close (MC) and auto-reclose (AR) functionality.
Close CB Pulse
The duration of the CB Close Pulse is settable to allow a range of CBs to be used. The Close pulse will be
terminated if any protection pick-up operates or a trip occurs. This is to prevent Close and Trip Command pulses
existing simultaneously. A 79 Close On Fault Output is given if a pick-up or trip operates during the Close Pulse.
This can be independently wired to Lockout.
'CB Failed To Open' and 'CB Failed to Close' features are used to confirm that a CB has not responded correctly
to each Trip and Close Command. If a CB fails to operate, the DAR feature will go to lockout.
'CB Close Fail' is issued if the CB is not closed at the end of the close pulse, CB Close Pulse.
Reclaim Timer
©2012 Siemens Protection Devices Limited
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7SR11 & 7SR12 Description Of Operation
Chapter 1 Page 59 of 76