MAINTENANCE
Page 18
Table 2 – Check Points for Periodic Inspection (cont.)
Check
Point
Check Item
Check Method
Criteria
What to do
Main Circuit
Dust on
surface of
vacuum
interrupter
Visual inspection.
Make sure there is no
dust on the surface.
Wipe with a clean,
dry cloth.
Insulation
Frame and
Flanges
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.
Control
Circuits
Auxiliary
Switch
See Electrical Service
Life (Page 22) and
Table 3.
Contact wear and
wipe. Make sure there
is no dust.
Replace if wear or
damage is
excessive. See
(Table 1) for
tightening torque
specifications
Drive unit
Visual inspection.
Check for overheating
and discoloration.
Contact factory.
Wiring
Visual inspection.
Tighten using a
screwdriver.
Check for
discoloration and
tightness.
Repair if
disconnected.
Tighten if loose.
See (Table 1) for
tightening torque
specifications.
Insulation
Resistance
Measure-
ment
Resistance
from main
circuit to
ground
Measure insulation
resistance between
phases, between
electrodes, and
between circuits and
ground. Megger test
at 1000V.
Resistance should be
100M
Ω
or greater.
Resistance
from control
circuits to
ground
Measure insulation
resistance between
circuits and ground.
Megger test at 500V.
Resistance should be
5M
Ω
or greater.
If the insulation
resistance is low,
wipe off the vacuum
interrupter and other
insulation surfaces
with a clean dry
cloth and then
repeat the test. If
necessary, replace
faulty parts.
