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9. Maintenance
Maintenance operations are aimed at ensuring
trouble-free operation of the apparatus for the
longest possible time.
In accordance with the specifications of the IEC
61208 / DIN 31 051 Standards, the following op-
erations must be carried out.
Inspection:
Determination of the actual con-
ditions
Servicing:
Measures to maintain the speci-
fied conditions
Repair:
Measures to restore the speci-
fied conditions.
9.1. General
Vacuum circuit-breakers are characterized by
their simple and sturdy construction and long life.
The operating mechanism requires minimum
maintenance and the vacuum interrupters are
maintenance-free for their whole operating life.
Vacuum interruption does not cause any harm-
ful effects even in the presence of frequent trips
at the rated and short-circuit currents.
The servicing interventions and their aim depend
on environmental conditions, the sequence of
operations and trips under short-circuit.
Note
The following Standards must be observed for
all maintenance work:
– the relevant specifications indicated in the
“Standards and specifications” chapter;
– the safety in the work place regulations given
in the “Putting into service and Operation” chap-
ter;
– the standards and specifications in the coun-
try of installation.
Maintenance work can only be performed by
trained personnel, observing all the safety regu-
lations.
It is recommended that ABB service personnel
should be called in, at least to check the service
performances and for repair work.
While the work is in progress, turn the power
supply off and put the apparatus under safe con-
ditions.
Before carrying out any operations,
check that the circuit-breaker is open,
with the springs discharged and that it
is not supplied (medium voltage circuit
and auxiliary circuits).
9.1.1. Operating life
Typical life-expectancies for VD4 circuit-break-
ers:
– vacuum interrupters: up to 30,000 operations,
depending on their type (see paragraph 7.2.3.);
– actuator: up to 30,000 operations under nor-
mal operating conditions, depending on the type
of circuit-breaker and with regular maintenance.
9.2. Inspection and functional testing
9.2.1. Interruption devices in general
– Carry out regular inspections to verify the good
condition of the interruption devices.
– Inspection at fixed intervals can be waived if
the switchgear is permanently monitored by
qualified personnel.
– Above all, the checks must include a visual
inspection to find any contamination, traces of
corrosion and electrical discharge phenomena.
– When there are unusual operating conditions
(including adverse climatic conditions) and/or
in the case of environmental pollution (e.g.
heavy contamination or an atmosphere with
aggressive agents), inspection must be car-
ried out more frequently.
– Visual examination of the isolating contacts.
Turning the contacts alternately is recom-
mended, in order to keep the internal surface
of the contact areas clean. The contact areas
must be cleaned if there are signs of over-
heating (discoloured surface) (also see the
paragraph on “Repairs”).
– If any anomalous conditions are found, appro-
priate servicing measures must be taken (see
the paragraph on “Servicing”).
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