Interlock Application Scheme # 6 - Isolating Switches and Breaker

Contents | Introduction | Symbols Legend | Scheme Book

Interlock Application - Isolating Switches and Breaker

Scheme # 6
To prevent operation of disconnect switch A when breakers B, C, D and E are closed. Breakers may be opened in any sequence.

NOTE: Electrical circuit is equivalent of Scheme 7.

Disconnect A and breakers B, C, D and E are shown in closed position. Key A-1 is held in transfer interlock. Keys A-2, A-3, A-4 and A-5 are held in interlocks on breaker B, C, D and E.

1.
2.

3.
4.

5.

6.
7.

8.

9.

Open breakers B, C, D and E.
Turn key in L-O interlock on each breaker B, C, D and E to lock breakers open. Keys A-2, A-3, A-4 and A-5 are now free.
Insert keys A-2, A-3, A-4 and A-5 in transfer interlock.
Turn key A-1 in transfer interlock. Key A-1 is now free. Keys A-2, A-3, A-4 and A-5 are now held.
Insert key A-1 in L-O-C interlock on disconnect A and turn to unlock. Key A-1 is now held.
Open disconnect A.
Turn key A-1 in L-O-C interlock on disconnect A to lock open. Key A-1 is now free.
Insert key A-1 in transfer interlock and turn. Key A-1 is now held, Keys A-2, A-3, A-4 and A-5 are now free.
Return keys A-2, A-3, A-4 and A-5, as desired, to breaker interlocks and unlock for operation during servicing.

Reverse sequence to restore service.

Links for more interlock application scheme information:

Contents | Introduction | Symbols Legend | Scheme Book

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