Siemens SGIM-3268H Manual Download

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Maintenance

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 each pole not under test.
3. Apply test voltage across each pole for one minute.
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 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. A permanent record of
periodic As-Found tests enables the maintenance organiza-
tion to determine when corrective actions are required by
watching for significant deterioration in insulation resist-
ance, 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 3

, the following equipment is

also required:

• AC High Potential tester with test voltage of 1500

volts, 60 Hz.

• Ductor for contact resistance tests.

Insulation and Contact Resistance Test Procedure

1. Observe safety precautions listed in the danger and

warning advisories for the Vacuum Integrity Check tests.

2. Close the circuit breaker. Ground each pole not under

test. Use manual charging, closing and tripping
procedures.

3. Apply the proper AC (i.e., either 14 or 27kV) or DC

(i.e., either 20 or 38kV) high potential test voltage
between a primary conductor of the pole and ground
for one minute.

4. If no disruptive discharge occurs, and the test voltage

is sustained for that period, the insulation system is
satisfactory.

5. After test, ground both ends and the middle of each

vacuum interrupter to dissipate any static charge.

6. Disconnect the leads to the spring charging motor.
7. Connect all points of the secondary disconnect with a

shorting wire. Connect the shorting wire to the high
potential lead of the high voltage tester, and ground the
circuit breaker housing. Starting with zero volts, gradu-
ally increase the test voltage to 1500 volts, RMS, 60 Hz.

Maintain test voltage for one minute.

8. If no disruptive discharge occurs, the secondary

control insulation level is satisfactory.

9. Disconnect the shorting wire and re-attach the leads to

the spring charging motor.

10. Perform contact resistance tests of the primary

contacts using a ductor. Contact resistance should not
exceed the values listed in

Table 4

11. Make a permanent record of all tests performed.

Inspection and Cleaning of Circuit Breaker Insulation

1. Perform the Spring Discharge Check on the circuit

breaker,

after

all control power is removed. The Spring

Discharge Check consists of 1) depressing the red Trip
pushbutton, 2) then depressing the black Close push-
button, and 3) again depressing the red Trip
pushbutton. All of these controls are on the circuit
breaker front panel. Visually verify the Discharge
condition of the springs.

2. Remove any interphase and outer phase barriers as

shown in

Figure 13

3. Clean barriers and post insulators using clean cloth

and one of the following cleaning solvents:

• No. 1 or No. 2 denatured alcohol

• Isopropyl or isobutyl alcohol

4. Replace all barriers. Check all visible fasteners again for

condition and tightness.

Functional Tests

Refer to the Installation Checklist in the Installation Checks
and Initial Functional Tests section of this manual.
Functional tests consist of performing at least three (3)
Manual Spring Charging Checks and three (3) Automatic
Spring Charging Checks. After these tests are complete, and
the springs fully discharged, all fasteners and connections
are checked again for tightness and condition before re-
installing the circuit breaker into the metal-clad switchgear.

uiip

ntt

V R

attiin

x A

C R

x D

C A

4.76kV

14kV

20kV

8.25kV