TAVRIDA ELECTRIC VCB Series, User Manual, Page: 101 / 142

101
7.1 Primary circuits
Under normal operating conditions (see Table 1) the ISM is maintenance free for a period of at least 30 years
or until it has reached the permissible number of operating cycles.
However when maintenance is carried out on the switchgear then the commissioning tests should be repeated.
Check that the ISM is disconnected from all voltage sources before inspecting its insulating parts. Test results
should be treated as given in Table 18.
Table 18 - List of tests and check-ups of ISM during maintenance
Operation description Required tool Approximate timing
Check for damage, remove any dirt, conta-
mination or moisture Dry napless cloth or a napless cloth soaked
in alcohol to clean the insulation
5 minutes
Bolts and torques shall be according to Figure
61 - Figure 67 Torque wrench according to torque value 2 minutes
Protective earthing shall be according to
subchapter 4.1.8 Wrench if required 1 minute
ISM operation check
Perform close and open operation of the ISM.
Modules shall be operable. Otherwise, check
the control circuit. If necessary, change the
failed module. Visual check, no tool is required 1 minute
Primary circuits insulation check
1)
Observe safety precautions listed in the danger
and warning advisories. Construct the proper
barrier and warning light system Equipment to provide safety in test area 10 minutes
Ground each pole not under test Wires 2 minutes
Apply slowly rising 100%
2)
of test voltage
3)
(50 or 60 Hz) across each pole for one minu-
te
4)
. (ISM is open)
Power frequency withstand voltage test set 2 minutes
If the pole sustains the test voltage for that
period, its vacuum integrity has been verifed
5)
Power frequency withstand voltage test set -
Repeat actions above to check each pole of the
ISM Power frequency withstand voltage test set,
wires
8 minutes
Close the ISM. Ground each pole not under test Wires 1 minute
Apply slowly rising 80% of test voltage
2)
(50 or
60 Hz) between a primary conductor of the pole
and ground for one minute, repeat test for each
pole of ISM
Power frequency withstand voltage test set 12 minutes
If no disruptive discharge occurs, the insulation
system is satisfactory Power frequency withstand voltage test set -
After the test, ground all main circuit terminals
to dissipate any static charge Wires 2 minutes
1) This test includes not only the vacuum interrupter test, but also the other insulation components tested in parallel with the interrupter. These include
the support insulators and the insulated drive links, as well as the insulating (tension) struts between the upper and lower vacuum interrupter
supports. If these insulation components are contaminated or defective, the test voltage will not be sustained. If so, clean or replace the affected
components, and retest.
2) For test of separate VCB - 100% level of test voltage, for test of Switchgear with installed VCB - 80% level of test voltage according to
IEC 62271-200.
3) Rated test voltage levels (Ud) are given in Table 1 above.
4) To apply test voltage the single-core short cables should be used. Application of high voltage coaxial cables is strictly prohibited. To coordinate the
surge impedance between the test set and ISM extra resistor as shown in Figure 154 shall be used.
5) During testing of vacuum interrupter, self-fading restrikes may appear. In case of restrikes, reduce the voltage slightly until the restrikes disappear
(for 10-15 seconds) and then increase again.