Maintenance; General; Inspection And Functional Testing; Switching Devices In General - ABB VD4 Instruction Manual

7 Maintenance

Maintenance serves to ensure trouble-free operation and
achive the longest possible working life of the switchgear.
It comprises the following closely related activities:
Inspection: Determination of the actual condition
Servicing: Measures to maintain the specified condition
Repair: Measures to restore the specified condition

7.1 General

(Figure 7/1)
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 sequences and
number of short-circuit breaking operations.
With carefully performed inspections and servicing work,
and under normal operating conditions, the circuit-breakers,
depending on the type, have a service life of up to 30,000
operating cycles and more.
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 Xiamen Switchgear Limited Co.
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 auxiliary voltage sources
m us t al so b e d is con nect e d a nd sec ur ed t o pr eve nt
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 cover plates 50.6 and 50.7 removed.
The spiral spring in the spring energy strage mechanism,
for instance, retains a basic tension which is independent
of the charging and discharging processes during
switching, so as to ensure correct function. This spring
energy can be inadvertently released if work is performed
incorrectly on the spring mechanism!

7.2 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.
Under normal operating conditions, testing by a qualified
personnel is to be performed at least every 4 years.
In unusual operating conditions (including adverse climatic
conditions) and/or special environmental pollutions (e.g.
heavy contamination and aggressive atmosphere), inspection
may also be necessary at shorter intervals.
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
f or cont am ination, corrosion, moist ur e and dischar ge
phenomena.
If an incorrect condition is found, appropriate servicing
measures are to initiated.

7.2.2 Stored-energy spring mechanism

(Figures 7/2 to 7/5)
Functional testing of the operating mechanism is to be
performed:
after 5000 operating cycles or during servicing work as set
■
out in 7.2.1.
Prior to functional testing, switch the breaker off and
■
isolate the outgoing feeder.
Scope of functional testing:
Perform several switching operations under no load, above
■
all with circuit-breakers seldom operated in normal service.
Switch off the charging motor (if fitted) and discharge
■
the spring mechanism by ON/OFF switching operations.
Examine visual the condition of the lubrication on rotary
■
bearings, sliding surfaces, etc.
Check the proper mechanical/electrical sequence of the
■
individual functions.
Check circuit-breaker's appearance.
■

7.2.3 Checking auxiliary switch settings on withdrawable part

(Figures 6/4, 6/6, 2/5 and 7/2)
Compliance with the interlock conditions in the areas of
the test/disconnected position and the service position is
ensured by auxiliary switches S8 and S9, located in the
breaker housing.
In test operations, the withdrawable part must be moved by
hand with the crank 146 fitted.
1. Settings in the area of the test/disconnected position
VD4 Vacuum Circuit-breaker | Maintenance 25