45
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
Overhauling:
Measures to be taken to maintain the specific condi-
tions
Repairs:
Measures to be taken to restore the specific condi-
tions.
9.1. General
The vacuum circuit-breakers are characterised by simple, sturdy
construction and a long life.
The operating mechanism requires maintenance and functional in-
spections to reach the expected operating-life (see par. 9.3.2.).
The vacuum interrupters are maintenance-free for their whole operat-
ing life.
Vacuum interruption does not produce any harmful effects even when
there are frequent interruptions at the rated and short-circuit current.
The interventions during service and their aim are determined by the
ambient conditions, by the sequence of operations and by the short-
circuit interruptions.
Note
Respect the following Standards for maintenance work:
– the relative specifications given in the chapter on “Standards and
Specifications”;
– work 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 per-
sonnel and who follow all the safety regulations. Furthermore, it is
advisable to call on 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 cir-
cuit-breaker is open, with the spring discharged and that
it is not supplied (medium voltage circuit and auxiliary
circuits).
9.1.1. Operating life expectancy
The operating life expectancy for the VD4 circuit-breakers is as fol-
lows:
– vacuum interrupters: up to 30,000 operations, according to their
type (see par. 7.2.3. Trip curves);
– switching device, 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 manually operated components (moving parts of isolatable
parts, etc.) can vary their behaviour.
– Visual inspection of the isolating contacts.
It is recommended 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 (discol-
oured surface) (also see Repairs).
– In the case of abnormal conditions, take suitable overhauling meas-
ures (see Overhauling par.).
9.2.2. Stored energy operating mechanism
Carry out the functional test of the operating mechanism after 5,000
operations (2,000 operations
for 3150 A circuit-breakers) or during
ordinary maintenance operations as specified in par. 9.2.1.
Before doing the test, open the circuit-breaker and carry out the fol-
lowing operations:
– in the case of withdrawable circuit-breakers, take the circuit-breaker
to 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 regula-
tions 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 foreseen, cut the power supply to the spring charging motor off.
Discharge the spring by closing and opening the circuit-breaker by
means of the closing and opening pushbuttons.
– Visually inspect the lubrication conditions of the tulip isolating con-
tacts, of the sliding surfaces, etc.
– Check correct electrical and mechanical operation of the various
devices, with particular attention to the interlocks.
– The screws and nuts are tightened in the factory and correct tight-
ening is marked with a collared sign. No further tightening opera-
tions are foreseen during the operating life of the circuit-breaker.
However, following any maintenance interventions, should it be nec-
essary to re-tighten the screws or nuts, it is recommended to al-
ways replace the screws and nuts and to keep to the values indi-
cated in fig. 12.
– Check the main actuator lever roller bearing lubrication (see details
A of fig. 13): it is advisable to lubricate with a few drops of SAE 80W/
90 type oil, using a special oiler.
Proceed as follows:
– remove the circuit-breaker screen
– charge the operating mechanism spring and lubricate the right-
hand bearing (circuit-breaker seen from the front - see fig. 13)
– close the circuit-breaker and lubricate the left-hand bearing (circuit-
breaker seen from the front- see fig. 13).
9.2.3. Circuit-breaker pole
No other check except what has already been specified in par. 9.2.1.
is necessary.
9.2.4. Withdrawable assembly (truck and circuit-breaker)
Visually inspect the components, especially those which may be dam-
aged by incorrect operations (also see table in chap. 8).
Visually inspect the isolating contacts and that all the contact ele-
ments are clean, especially in cases where signs of overheating are
found (also see par. 9.4.).
Visually inspect and carry out the functional tests of the locks, check-
ing their correct operation and activation without abnormal force –
maximum 25 N (also see table in chap. 8).
9.2. Inspections and functionality tests
9.2.1. Interruption devices in general
– Check the conditions of the interruption devices with regular in-
spections.
– 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 phe-
nomena.
– Carry out more frequent inspections when there are unusual oper-
ating conditions (including severe climatic conditions) and in the
case of environmental pollution (e.g. high level of contamination or
an atmosphere with aggressive agents).
