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9. Maintenance
The maintenance operations are aimed at keeping the
apparatus in good working condition for as long as possible.
In accordance with what is specified in the IEC 61208 / DIN
31 051 Standards, the following operations must be carried
out.
Inspection: Finding out the actual conditions
Servicing:
Measures to be taken to maintain the specific
conditions
Repairs:
Measurements to be taken to restore the
specific conditions.
9.1. General information
Vacuum circuit-breakers are characterised by simple, sturdy
construction and a long life.
The operating mechanism requires maintenance and
functional inspections to reach its expected operating-life (see
par. 9.3.2.).
The vacuum interrupters are maintenance-free for their whole
operating life.
Vacuum interruption does not produce any harmful effects
even when there are frequent trips at the rated and short-
circuit current.
The interventions during service and their aim are determined
by environmental conditions, by the sequence of operations
and by the short-circuit trips.
Note
Comply with the following Standards for maintenance work:
– the relative specifications given in the chapter on “Standards and Specifications”;
– labour safety regulations in the chapter on “Putting into service and operations”;
– standards and specifications of the country where the apparatus is installed.
The maintenance operations must only be carried out by
trained personnel who follow all the safety regulations.
Furthermore, it is advisable to call in ABB personnel, at least
in cases for checking the performances in service and for
repairs.
Cut the power supply off and put the apparatus under safe
conditions during the maintenance operations.
Before carrying out any operations, check that the
circuit-breaker is open, with the spring discharged
and that it is not powered (medium voltage circuit
and auxiliary circuits).
9.1.1. Operating life expectancy
The operating life expectancy for the eVD4 circuit-breakers is
as follows:
– vacuum interrupters: up to 30,000 operations, according to
their type (see par. 7.2.3. Trip curves);
– actuator and transmission system: up to 30,000 operations,
under normal operating conditions, according to the type
of circuit-breaker and with regular maintenance (see par.
9.3.2.);
– with operations correctly executed it is possible to carry out
up to 1000 racking-out/in operations (as prescribed in the
IEC 60271-200 Standards);
– the data regarding the operating life are basically applicable
to all the components which cannot be directly affected
by operator activity. The behaviour of manually operated
components (moving parts of isolatable parts, etc.) can
vary.
9.2. Inspections and functional tests
9.2.1. Breaking devices in general
– Check the conditions of the interruption devices with regular
inspections.
– Inspection at fixed intervals can be avoided when the
apparatus is permanently under the control of qualified
personnel.
– The checks must, first of all, include visual inspection
to check for any contamination, traces of corrosion or
electrical discharge phenomena.
– Carry out more frequent inspections when there are unusual
operating conditions (including severe climatic conditions)
and in the case of environmental pollution (e.g. high level of
contamination or an atmosphere with aggressive agents).
– Visual inspection of the isolating contacts. Remember to
turn the contact system alternately in order to keep the
internal surface of the contact areas clean. The contact
areas must be cleaned when there are signs of overheating
(discoloured surface) (also see Repairs).
– In the case of abnormal conditions, take suitable servicing
measures (see Servicing par.).
9.2.2. Stored energy spring operating mechanism
Carry out the functional test of the operating mechanism after
5,000 operations or during normal maintenance operations as
specified in par. 9.2.1.
Before doing the test, open the circuit-breaker and carry out
the following operations:
– in the case of withdrawable circuit-breakers, set the circuit-
breaker in the isolated for test position
– in the case of fixed circuit-breakers: cut off the power
supply to the medium voltage circuit.
Note
Insulate the work area and make it safe, following the safety regulations specified in
the IEC/DIN VDE Standards.
Functional test
– With the circuit-breaker not connected to the load, carry out
a few opening and closing operations.
– If required, cut off the power supplied to the spring loading
motor. Release the spring by closing and opening the
circuit-breaker with the closing and opening pushbuttons.
– Visually inspect the lubrication conditions of the tulip
isolating contacts, of the sliding surfaces, etc.
– Check correct electrical and mechanical operation of the
various devices, with particular attention to the interlocks.
Summary of Contents for eVD4
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