Primary Circuits - TAVRIDA ELECTRIC VCB Series User Manual

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.
Operation description
Check for damage, remove any dirt, conta-
mination or moisture
Bolts and torques shall be according to Figure
61 - Figure 67
Protective earthing shall be according to
subchapter 4.1.8
Perform close and open operation of the ISM.
Modules shall be operable. Otherwise, check
the control circuit. If necessary, change the
failed module.
Observe safety precautions listed in the danger
and warning advisories. Construct the proper
barrier and warning light system
Ground each pole not under test
Apply slowly rising 100%
(50 or 60 Hz) across each pole for one minu-
4)
te . (ISM is open)
If the pole sustains the test voltage for that
period, its vacuum integrity has been verifed
Repeat actions above to check each pole of the
ISM
Close the ISM. Ground each pole not under test
Apply slowly rising 80% of test voltage
60 Hz) between a primary conductor of the pole
and ground for one minute, repeat test for each
pole of ISM
If no disruptive discharge occurs, the insulation
system is satisfactory
After the test, ground all main circuit terminals
to dissipate any static charge
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.
Table 18 - List of tests and check-ups of ISM during maintenance
Dry napless cloth or a napless cloth soaked
Torque wrench according to torque value
Primary circuits insulation check
Equipment to provide safety in test area
2) 3)
of test voltage Power frequency withstand voltage test set
Power frequency withstand voltage test set
5)
Power frequency withstand voltage test set,
2)
(50 or Power frequency withstand voltage test set
Power frequency withstand voltage test set
Required tool
in alcohol to clean the insulation
Wrench if required
ISM operation check
Visual check, no tool is required
Wires
wires
Wires
Wires
Approximate timing
5 minutes
2 minutes
1 minute
1 minute
1)
10 minutes
2 minutes
2 minutes
8 minutes
1 minute
12 minutes
2 minutes
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