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Section 7
Commissioning and maintenance of the fault clearing system
7.1.2.1
7.1.2.2
144
The normal maintenance practices of the user should be followed. However, ABB's
recommendation is as follows:
Every second to third year
•
Visual inspection of all equipment.
•
Removal of dust on ventilation louvres and IEDs if necessary.
•
Periodic maintenance test for protection IEDs of object where no redundant
protections are provided.
Every four to six years
•
Periodic maintenance test for protection IEDs of objects with redundant protection
system.
First maintenance test should always be carried out after the first half
year of service.
When protection IEDs are combined with built-in control, the test
interval can be increased drastically, up to for instance 15 years,
because the IED continuously reads service values, operates the
breakers, and so on.
Visual inspection
Prior to testing, the protection IEDs should be inspected to detect any visible damage
that may have occurred (for example, dirt or moisture deposits, overheating). Should
burned contacts be observed when inspecting the IEDs, a diamond file or an extremely
fine file can be used to polish the contacts. Emery cloth or similar products must not be
used as insulating grains of abrasive may be deposited on the contact surfaces and
cause failure.
Make sure that all IEDs are equipped with covers.
Maintenance tests
To be made after the first half year of service, then with the cycle as proposed above
and after any suspected maloperation or change of the IED setting.
Testing of protection IEDs shall preferably be made with the primary circuit de-
energized. The IED cannot protect the circuit during testing. Trained personnel may
1MRK 506 331-UUS A
Commissioning Manual
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