650997/032 M3349 - 1999/11/03 fr-en - Rev. 6-2002 - 51/56
ITEM TO BE CHECKED
Cubicles
Connections of the power circuit
Earthing busbar and relative con-
nections
Insulation
Circuit-breakers
Switch-disconnector and earth-
ing switch
Auxiliary service and control cir-
cuits
NOTES
Check efficiency of earthing according to the
accident prevention Standards
– The value of the insulation resistance cam be
affected by ambient conditions.
– If the low insulation resistance value is due to
ambient humidity, use temporary pre-heating
devices.
Disconnect the MV cables during measure-
ment.
Example:
–
Rated voltage of the switchboard: 24 kV
– Required test voltage: 50 kV for 1 min. a.c.
(carried out in the factory)
– Test voltage after installation: 0.8 x 50 = 40 kV
for 1 min.
The spare key to each lock must be placed some-
where inaccessible to the personnel running the
installation.
The spare key to each lock must be placed some-
where inaccessible to the personnel running the
installation.
Before this control, check the settings of all the
various relays installed in the switchboard.
OPERATIONS
–
Visually check both the inside and outside, making sure
there is no obvious damage. Remove any foreign bodies
(such as tools or test connections which may have been
forgotten during the installation stage).
– Carefully clean the insulating parts, removing any trace of
humidity or dust with a clean dry cloth.
– Check that all the screws are tightened correctly.
– Check that all the end sheets and those foreseen in the
configuration constructed are mounted correctly.
– Check correct installation of all the segregation sheets
against any accidental contacts.
– Check operation of the interlocks and that the keys (if
present) are correctly joined together with the ring welded
according to the nameplate operation sequence.
– For internally arc proof version switchboards, check that
the stack and gas exhaust openings (busbar duct, outgoing
compartment) are fixed with screws and thermoplastic
rivets.
– Check that the mechanical service operations can be
carried out using normal activating force (
£
200 N).
– Check correct positioning of the isolators through the
inspection windows.
– Check that the shields and field distributors are mounted
correctly.
The force interlocks resist a maximum stress
of 750 N.
Check tightness
Check tightness and continuity
– Using a 2500 V Megger, measure the insulation resistance
of the power circuits (phase-phase and phases-earth)
and with a 500 V Megger, the insulation resistance of the
auxiliary circuits.
For each cubicle the value determined must be at least
5000 M
W
for the power circuits and more than a few M
W
for the auxiliary circuits.
The insulation resistance must remain constant over time
even after any voltage tests
The test voltage applied after installation is not required by
the CEI 17-6 Standards.
If the user thinks it necessary, it must be carried out at a
value equal to 80% of the value indicated under point 7.1. of
the IEC 694 Standard and only in alternating current.
– Carry out the operations prescribed in the instruction
manual on each piece of apparatus before putting into
service.
– Check presence of the operating devices and accessories
provided for normal operation.
– Insert the apparatus in the relative compartments and
connect the plugs of the auxiliary circuits.
– Close the compartment doors.
– Carry out the operations prescribed in the instruction
manual on each piece of apparatus before putting into
service.
– Check presence of the operating devices and accessories
provided for normal operation.
According to the switchboard key diagram, check function-
ality and service sequence of the automatisms of all the
auxiliary relays
!
Summary of Contents for UniAir
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