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7
Maintenance
Maintenance serves to ensure trouble-free
operation and achieve the longest possible work-
ing life of the switchgear. In accordance with
DIN 31 051 / IEC 61208 it comprises the following
closely related activities:
Inspection:
Determination of the actual condition
Servicing:
Preservation of a functional condition
Repair:
Measures to restore the functional
condition.
7.1
General
Vacuum circuit-breakers are characterized by
their simple and robust construction. They have a
long life expectancy. Their operating mechanisms
have a low maintenance requirement, and the
interrupters are maintenance-free during their
working life. There is no adverse effect on the
vacuum, even from frequent switching of operating
and short-circuit currents.
The servicing intervals and scope are determined
by environmental influences, the switching sequen-
ces and number of short-circuit breaking
operations.
Note:
The following must be observed for all maintenance
work:
• The relevant specifications in section 1.2.2
• Notes on safety at work in section 6.1
• Standards and specifications in the country of
installation.
Maintenance work may only be performed by fully
trained personnel, observing all the relevant safety
regulations. It is recommended that ABB after-
sales service personnel should be called in, at least
during the performance of servicing and repair work.
While the work is in progress, all supply voltage
sources must also be disconnected and secured
to prevent reconnection.
Note:
In order to prevent accidents (particularly injury to
hands!) extreme care should be taken during
all repair work on the operating mechanism,
especially with front plate removed.
The spiral spring in the spring energy store, for
instance, retains a basic tension which is inde-
pendent of the charging and discharging proces-
ses during switching, so as to ensure correct
function. This spring energy can be inadvertently
released if work is performed incorrectly on the
spring mechanism!
7.1.1
Service life
Typical life expectancies for VD4 circuit-breakers:
• Breakers with rated short-circuit breaking
currents up to 50 kA:
– The maintenance-free vacuum interrupters
up to 30,000 operating cycles (see section
2.4).
– The breaker itself, depending on type and
presupposing carefully performed inspection
and servicing work and normal operating
conditions, up to 30,000 operating cycles.
• Breakers rated short-circuit breaking currents
63 kA:
– Vacuum interrupters and breakers up to
10,000 operating cycles.
The service life data fundamentally apply to all
components which are not directly influenced by
the operator.
Components operated manually (movement of the
withdrawable part, etc.) may deviate.
7.2
Inspection and functional testing
7.2.1
Switching devices in general
• The proper condition of the switching device is
to be verified by regular inspection.
• The checks are to be performed in accordance
with BGV A2 standard.
• Inspection at fixed intervals may be waived if the
switchgear is permanently monitored by a
qualified personnel.
• The checks first and foremost comprise visual
examination for contamination, corrosion,
moisture and discharge phenomena.
• In unusual operating conditions (including
adverse climatic conditions) and/or special envi-
ronmental pollutions (e.g. heavy contamination
and aggressive atmosphere), inspection may
also be necessary at shorter intervals.
• If an incorrect condition is found, appropriate
servicing measures are to be initiated.
7.2.2
Stored-energy spring mechanism
(Figures 7/1 to 7/4)
Functional testing of the operating mechanism is to
be performed:
Breakers with rated short-circuit breaking current
with 50 kA:
• after 5,000 operating cycles or
• during servicing work as set out in 7.2.1.
Breakers with rated short-circuit breaking current
with 63 kA:
• after 2,000 operating cycles or
• during servicing work as set out in 7.2.1.
