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No. Location Item Inspection
method
Criteria Disposition Remarks
3 Insulator Dust, foreign
matter or
damage
Visual
inspection.
Make sure there
is no dust,
foreign matter or
breakage.
Wipe with a
clean dry cloth.
If damaged,
contact
Toshiba.
4 Auxiliary
switch
Terminals
loose or
disconnected
Visual
inspection.
Tighten using a
screwdriver.
Make sure
terminals are not
loose or
disconnected.
Repair if
disconnected.
Tighten if
loose.
See Table 5
for
tightening
torque.
Case/contacts Visual
inspection
Make sure there
is no damage or
Warping.
Replace if
damaged or
warped.
5 Control
circuits
Smooth
movement
when
electricity is
supplied
Supply
electricity to
operate the
circuit.
Make sure circuit
operates
smoothly.
If circuit fails to
operate, check
the cause and
repair.
Terminals
loose or
disconnected
Visual
inspection.
Tighten using a
screwdriver.
Make sure
terminals are not
loose or
disconnected.
Repair if
disconnected.
Tighten if loose
See Table 5
for
tightening
torque.
6 Insulation
resistance
measurement
If the insulation
resistance
between the
main circuit
terminals is
low, wipe the
vacuum valve
and insulator
surface with a
clean dry cloth
and repeat the
test.
5.5 Vacuum Check
A sufficient level of vacuum is necessary for proper performance of the vacuum interrupters. Although
vacuum leaks are rare, the vacuum integrity should be checked periodically. The relationship between
dielectric breakdown voltage of the contact gap and internal vacuum interrupter pressure has been found
to be generally predictable. Therefore, vacuum interrupter integrity is checked by performing a high
potential test across the open gap of the interrupter.
TEST EQUIPMENT:
Measurement
point
Insulation
resistance
Tester
Main conductor to
ground
500M
or greater
1000 V
Group of control
circuits to ground
2M
or greater
500 V
Between main
circuit
terminals
100M
or greater
1000 V