M ED I U M VO LTAG E P R O D U C T S
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9. Maintenance
The purpose of the maintenance operations is to
keep the apparatus in a good working condition
for as long as possible.
The following operations must be performed, as
specified in Standards IEC 61208 / DIN 31 051.
Inspection: Establishing the real conditions
Overhaul:
Measures to be taken to maintain
the specific conditions
Repair:
Measures to be taken to restore the
specific conditions.
Please refer to BS EN 13306:2010, clause 8, for
maintenance types definitions.
9.1 General
Vacuum circuit breakers are characterised by
simple, sturdy construction and a long life.
The operating mechanism is maintenance-free for
its whole operating life, and only requires
functional inspections (see sect. 9.2.2).
The vacuum interrupters are maintenance-free for
their whole operating life.
Vacuum interruption does not produce any
harmful effects even when there are frequent
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 shortcircuit
interruptions.
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 comply with all the
safety regulations. Furthermore, it is advisable to
have ABB personnel at least check the performance
during service and carry out any repairs required.
Cut the power supply off and put the apparatus
under safe conditions during the maintenance
operations.
Before proceeding with any operation, make
sure that the circuit breaker is open, with
the springs discharged and that it is not
powered (medium voltage circuit and
auxiliary circuits).
9.1.1 Operating life
The operating life expectancy of VD4 circuit
breakers is as follows:
•
vacuum interrupters: up to 30,000 operations,
depending on the type (see sect. 7.2.3 Trip
curves);
•
actuator and transmission system: up to 10,000
operations, under normal operating conditions,
depending on the type of circuit breaker and
with regular maintenance.
9.2 Inspections and functionality
tests
9.2.1 Interruption devices in general
•
Assess the conditions of the interruption
devices by conducting regular inspections.
•
Inspection at fixed intervals can be avoided
when the apparatus is permanently under the
control of qualified personnel.
•
Firstly, the assessments must include visual
inspection to check for any contamination,
traces of corrosion or electrical discharge
phenomena.
•
Performa 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. The
contact system should be turned 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 consult the Repairs section).
•
Conduct overhauls if the conditions are
abnormal (see Overhauling section).
9.2.2 Stored energy operating mechanism
Subject the operating mechanism to a functional
after 5,000 operations or after 4 years.
Before performing the test, open the circuit
breaker and deenergise the medium voltage
circuit.
Note
Insulate the work area and make it safe, following
the safety regulations specified in the IEC/DIN
VDE Standards.
