Siemens GMSG Instruction Manual page 51

Table 4: High-potential test voltages
Rated maximum Rated power-
voltage frequency withstand
kV (rms)
4.76
8.25
15.0
15.0 generator
circuit breaker
Vacuum-integrity test procedure
1. Observe safety precautions listed in the
DANGER and WARNING advisories.
Construct the proper barrier and
warning light system.
2. Ground the frame of the circuit
breaker, and ground each pole not
under test.
3. Apply test voltage across each pole for
one minute (circuit breaker OPEN).
4. If the pole sustains the test voltage for
that period, its vacuum integrity has
been verified.
Note: This test includes not only the
vacuum interrupter, but also the other
insulation components in parallel with the
vacuum interrupter. These include the
standoff 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.
As-found insulation and contact-
resistance tests
As-found tests verify the integrity of the
circuit breaker insulation system. Megger*
or insulation-resistance tests conducted on
equipment prior to installation provide a
basis of future comparison to detect
changes in the protection afforded by the
insulation system.
kV (rms) kV (rms)
19 14.25
36 27
36 27
38 28.5
A permanent record of periodic as-found
tests enables the maintenance
organization to determine when corrective
actions are required by watching for
significant deterioration in insulation
resistance, or increases in contact
resistance.
Insulation and contact-resistance test
equipment
In addition to the high-potential test
equipment capable of test voltages as
listed in Table 4: High-potential test
voltages, the following equipment is
required:
AC high-potential tester with test
voltage of 1,500 volts, 60 Hz
Test equipment for contact-resistance
tests.
Insulation and contact-resistance test
procedure
1. Observe safety precaution listed in the
DANGER and WARNING advisories for
the vacuum-integrity check tests.
2. Close the circuit breaker. Ground the
frame of the circuit breaker, and
ground each pole not under test. Use
manual charging, closing and tripping
procedures.
3. Apply the proper ac or dc high-
potential test voltage as shown in Table
4 between a primary conductor of the
pole and ground for one minute.
4. If no disruptive discharge occurs, the
insulation system is satisfactory.
Field-test voltage
kV dc
20.2
38.2
38.2
40.3
Maintenance
*Megger is a registered
trademark of Megger
Group, Ltd.
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