Sel 411L - Figure 12.6 Disconnect in Transition

P.12.12
SEL-411L Relay Protection Manual Date Code 20151029
Bay Control
Disconnect Logic
Figure 12.6 Disconnect in Transition
When the normally closed auxiliary contact (SELOGIC input 89BMm)
deasserts, the disconnect switch is in an undetermined state. No proper
position indication from either of the disconnect switch auxiliary contacts
(89BMm or 89AMm) is available. Once the auxiliary normally closed contact
(SEL
OGIC input 89BMm) deasserts, the 89ALPm timer starts timing. The
89ALPm timer monitors the undetermined state of the disconnect switch. For
the 89ALPm timer to initialize, the disconnect switch has to move a minimum
distance to open the normally closed auxiliary contact (open-to-close
operation). Set the 89ALPm timer longer than the expected undetermined
disconnect state time, and slightly longer than the 89CSTm seal-in timers in
the case the relay provides the seal-in circuit. When the 89CSTm seal-in timer
expires, the close disconnect switch output signal 89CLSm is cleared. Then
the disconnect switch is given some more time to complete the close operation
in case that the inertia on motor rotor keeps the disconnect motor moving.
89ALPm timer should not time out before 89CITm seal-in timer expires in
order to maintain close signal until the disconnect switch is completely closed.
If the normally open auxiliary contact fails to close within the allowed
undetermined state time, the 89ALPm timer expires and an alarm condition is
declared.
The close immobility logic starts the close immobility timer for an operation
where the disconnect switch does not move the minimum distance to open the
normally closed auxiliary contact (open-to-close operation). When the close
immobility timer expires, an alarm condition is declared and Relay Word bit
89ALm asserts. If the disconnect moves enough to open the normally closed
auxiliary contact, the close immobility timer resets and no alarm condition is
declared. See close immobility timer logic in Figure 12.4.
Disconnect Close
Command Issued
Disconnect Main
Contact in Transition
Disconnect Close
Operation Completed
89CIMTm Immobility
Timer Setting
Normally Closed b
Contact (89BMm)
Normally Open a
Contact (89AMm)
Expected Disconnect Operate Time
89BMm b Contact
Closed
89BMm deasserts and
89ALPm begins timing
89AMm a
Contact Closed
89ALPm Alarm
Time Setting
Undetermined State
89CSITm Seal-In Timer