Interlock Application Scheme # 9 - Isolating Switches and Breaker

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Interlock Application - Isolating Switches and Breaker

Scheme # 9
To prevent operation of disconnects A and B with breaker C closed. To prevent access to breaker compartment with disconnects closed.

Disconnects A and B, breaker C, and door are normally closed. Keys A-1 are held in L-O interlock on breaker C and L-O interlock on disconnect B. Key A-2 is held in the L-O interlock on disconnect A. Key A-3 is held in L-O interlock on disconnect B.

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2.

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11.

Open breaker.
Turn key A-1 in L-O interlock on breaker to lock open.
Key A-1 is now free.
Insert key A-1 in L-C interlock on disconnect A and
turn to unlock. Key A-1 is now held.
Open disconnect A.
Turn key A-2 in L-O interlock on disconnect A to lock
open. Key A-2 is now free.
Insert key A-2 in L-C interlock on disconnect B and
turn to unlock. Key A-2 is now held.
Open disconnect B.
Turn keys A-1 and A-3 in L-O interlock on disconnect
B to lock open. Keys A-1 and A-3 are now free.
Insert key A-1 in breaker L-O interlock and turn to
unlock for operation during servicing.
Insert key A-3 in L-C interlock (type D) on
compartment door and turn to unlock.
Key A-3 is now held.
Open compartment door to service breaker.

Reverse sequence to restore service.

Links for more interlock application scheme information:

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Scheme # 1
Scheme # 2
Scheme # 3
Scheme # 4
Scheme # 5
Scheme # 6
Scheme # 7
Scheme # 8
Scheme # 9
Scheme # 10
Scheme # 10A
Scheme # 11 Scheme # 12

Scheme # 13
Scheme # 14
Scheme # 15
Scheme # 16
Scheme # 17
Scheme # 17A Scheme # 18
Scheme # 19
Scheme # 20
Scheme # 21
Scheme # 22 Scheme # 23
Scheme # 24

Scheme # 25
Scheme # 26
Scheme # 27 Scheme # 28
Scheme # 29
Scheme # 30
Scheme # 31
Scheme # 32
Scheme # 33 Scheme # 34
Scheme # 35
Scheme # 35A
Scheme # 36

Scheme # 37
Scheme # 38 Scheme # 39
Scheme # 40
Scheme # 41
Scheme # 42
Scheme # 42A
Scheme # 42B
Scheme # 43
Scheme # 43A
Scheme # 44
Scheme # 45
Scheme # 45A