Toshiba HV6CS-MLD Test Procedure, replace the vacuum interrupter, Criteria, Voltage, Time

TEST PROCEDURE:

1. The circuit breaker should be disconnected from the main circuit and be in the OFF position.

2. Connect all the line side primary terminals together and to the output of the vacuum checker or AC hi-pot machine. Connect all the load side primary terminals together and to the ground terminal of the vacuum checker or AC hi-pot machine.

3. Increase the voltage from zero to 22kV AC at a rate of approximately 2kV per second. Hold the voltage at this value for 1 minute and observe the current drawn by the interrupter.

Note: If the ammeter fluctuates violently as the voltage increases to AC22 kV, repeat the voltage increase procedure two or three times. If the current still rises when the voltage is increased, the vacuum level may be insufficient;

replace the vacuum interrupter.

1 minute

4. Decrease the voltage back to zero.	22kV AC
	(31kV DC)
CRITERIA:
1. If a current flow above 5 milliamperes is observed or	Voltage
if breakdown occurs, one or more of the interrupters
has insufficient vacuum and must be replaced.
Exception: If the current exceeds 5 milliamperes the	Zero
first time the voltage is brought up, reduce the
voltage to zero and increase it again. It may be	15 sec	15 sec
necessary to repeat this procedure a few times.
		Time
2. If the breaker fails to meet criteria 1, then repeat the	Figure 24 Application of Test
	Voltage for Vacuum Check
test on each pole separately to identify the damaged
interrupter or interrupters.

3.If the voltage can be held for 1 minute and the current flow does not exceed 5 milliamperes, the interrupter has a sufficient vacuum level.

After the test is complete, discharge any residual static charge from the primary terminals of the circuit breaker.

If a vacuum checker or AC hi-pot tester is not available, a DC hi potential test may be conducted. If a DC test is conducted, the test voltage must be increased to 31kV DC. The test duration for DC tests and the criteria for acceptance remain the same as for AC tests.

WARNING

Do not use DC hi-pot testers which employ unfiltered half-wave rectifiers. The peak voltages produced by these testers may exceed the recommended value of 31kV. This can result in the production of harmful X-rays

and may invalidate the test results.

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