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Contents
| Introduction
| Symbols
Legend | Scheme
Book
Interlock
Application
- Prevent Paralleling of Lines
Scheme # 17
To
prevent paralleling of lines A, B, C, and D. Four loads,
fed from any source (three tie-breakers).

Breaker
A is closed to supply load M. Breaker B is closed to supply
load N. Breaker C is closed to supply load P. Breaker
D is closed to supply load R. Keys A-1, B-1, C-1, and
D-1 are held in L-O interlocks of breakers A, B, C, and
D. Breakers E, F and G are locked open. Breaker E interlock
has a master or apartment lock and can be unlocked for
operation with either key A-1 or B-1. Breaker F interlock
has a master or apartment lock and can be unlocked for
operation with either key B-1 or C-1. Breaker G interlock
has a master or apartment lock and can be unlocked for
operation with either key C-1 or D-1.
To transfer load M from breaker A to breaker B:
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1.
2.
3.
4.
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Open breaker A.
Turn key A-1 in L-O interlock on breaker A to lock
open. Key A-1 is now free.
Insert key A-1 in L-O interlock on tie-breaker E and
turn to unlock. Key A-1 is now held.
Close tie-breaker E. |
Reverse
sequence to restore service through breaker A.
To transfer load M and N from breaker A and B to breaker
C:
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1.
2.
3.
4.
5.
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Close tie-breaker E as above.
Open breaker B.
Turn key B-1 in L-O interlock on breaker B to lock
open. Key B-1 is now free.
Insert key B-1 in L-O interlock on tie-breaker F and
turn to unlock. Key B-1 is now held.
Close tie-breaker F. |
Reverse
sequence to restore service (M and N) through breakers
A and B.
To transfer load R from breaker D to breaker C:
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1.
2.
3.
4.
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Open breaker D.
Turn key D-1 in L-O interlock on breaker D to lock
open. Key D-1 is now free.
Insert key D-1 in L-O interlock on tie-breaker G and
turn to unlock. Key D-1 is now held.
Close tie-breaker G. |
Reverse
sequence to restore service through breaker D.

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