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Summary (1)
To assure ourselves, and the interested authorities, that the overall protective system functions correctly.
Study of wiring diagrams and protection requirements.
Careful delegation of responsibilities to reduce the duplication of effort and to ensure that all the following aspects are covered :-
> Commissioning & Maintenance of Protective Relays
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Minimum of time consumed
Unable to check :-
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Mechanical inspection
Contact follow-through and pressures
Electrical checks on each basic electrical function to prove satisfactory operation
Prove trip and alarm circuits
Test results (record and maintenance purposes)
> Commissioning & Maintenance of Protective Relays
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C.T. mag curve tests
Primary sensitivity tests
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resources
d) The risks involved if the protection should fail
e) The type of relay construction
> Commissioning & Maintenance of Protective Relays
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identical site conditions
or semi-automatic test facilities, and the
difficulties of alternative tests
failure, component or otherwise, that may go
undetected and leave the system unprotected
> Commissioning & Maintenance of Protective Relays
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Typically maintain every 12-18 months under ideal conditions and decrease frequency
> Commissioning & Maintenance of Protective Relays
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Calibration tests
Trip testing
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PROZONE
Contact cleaning burnishers
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(Protective Relay Application Guide)
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O.C. and E.F. relays
(Protective Relay Application Guide)
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(Protective Relay Application Guide)
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(if any)
A B C A B C N A B C N
> Commissioning & Maintenance of Protective Relays
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V Voltmeter
A Ammeter
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51
51
250V
A.C.
supply
A
B
C
51
64
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A
B
C
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87 Generator differential relay
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A
B
C
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Temporary
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Temporary
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Instantaneous current distribution for three-phase short circuit with phase A current at maximum
> Commissioning & Maintenance of Protective Relays
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A
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64 Earth Fault Relay
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46 Negative phase sequence relay
A Ammeter