Powered by Safety
®
61
Maintenance
01.4IB.67000
10) Battery and Charging Equipment
The control battery is such an important
accessary to the switchgear operation
that it must be given special periodic
attention if it is to have a long life of reliable
service. Periodic inspections and tests are
recommended in the battery supplier’s
instructions. During the same time that
the battery is routinely checked, inspect
the battery charger and remove and
accumulations of dust and dirt.
On all chargers, having a manual transfer
switch for setting the charging rate,
carefully check and ensure that the selector
switch is returned to the value appropriate
for a floating charge at the end of the
periodic inspection. Serious damage to the
control battery can occur if the charger is
left on a high charging rate for an extended
period of time.
11) Hardware
Check to see all anchor bolts and
switchgear hardware are tightened to
correct torque values. See Table C, Bolt
Torque Values.
12) Heaters
If the switchgear is equipped with
anti-condensation heaters, check to see
that all heaters are energized and operating
properly. This may be done by using a
hook-on ammeter to measure the current
drawn by the heater.
13) Testing
The condition of each switchgear unit at
the time of inspection should be listed in
a permanent record to become a guide for
anticipating the need for replacements or
for special attention between the regularly
maintenance periods.
a. Insulation resistance tests are suggested
for checking the insulation. A series of
these tests will indicate any tendency
toward a reduction in dielectric strength
of the insulation. Insulation resistance
readings should be taken before
and after cleaning the switchgear
equipment and, insofar as possible,
under similar conditions at successive
periods. Records should include the
insulation resistance reading, the
temperature, and the humidity (either
by definite reading or description).
b. Acceptable limits vary with the extent
and design of the bus structure. In
contrast to a small installation, the
longer switchgear assemblies have
a more extensive bus structure with
a greater number of insulators and
thereby, a larger number of parallel
insulation resistance paths to ground,
which will tend to decrease insulation
resistance readings. This variation in
insulation resistance between different
switchgear lineups emphasizes the
value of a series of readings that can be
charted to establish a normal insulation
level so that progressive weakening
of the insulation can be recognized.
Voltage transformers and control power
transformers should be disconnected
during these tests, as they may not be
able to withstand the switchgear tests
and they may provide direct paths to
ground.
To Next Page
Loading...