GE Industrial Solutions PowerVac PV-VL 13.8-1000-0 and -1 - Manual (Page 32)

Page 32 GEH 6468A - Power/Vac VL Breaker
vps to the test voltage and that voltage maintained
for 60 seconds. The voltage should then be returned
to zero and the hipot machine removed from the
circuit. Do not exceed the test voltage indicated for
the applicable breaker voltage rating.
12.2.2. SECONDARY CIRCUIT
Prior to hipotting the breaker secondary circuit,
disconnect the motor leads and thread a wire
connecting all secondary coupler pins. Increase the
voltage to 1125 volts (rms) 60 Hz and maintain for 60
seconds. Reduce the voltage to zero and remove the
hipot machine from the circuit. Remove the wire
connecting the secondary coupler pins and reconnect
the motor leads.
12.3. PRIMARY CIRCUIT RESISTANCE
A resistance check of the primary circuit may be
made with the breaker closed. Use a low resistance
measuring instrument which measures micro-ohms.
The 100 ampere reading should be 5 to 25 micro-
ohms for a 3000 amp breaker, 25 to 50 micro-ohms
for a 2000 amp breaker and 30 to 60 micro-ohms for
a 1200 amp breaker when connected across the
primary and secondary stabs on the breaker.
12.4. VACUUM INTERRUPTER INTEGRITY
TEST
CAUTION: X-RADIATION WILL BE
PRODUCED IF AN ABNORMALLY HIGH VOLTAGE
IS APPLIED ACROSS A PAIR OF ELECTRODES IN
A VACUUM. X-RADIATION WILL INCREASE AS
VOLTAGE INCREASES AND/OR AS CONTACT
SEPARATION DECREASES. ONLY TEST A
CORRECTLY-AD-JUSTED CIRCUIT BREAKER.
DURING A HIGH POTENTIAL OR A VACUUM
INTEGRITY TEST, ANY X-RADIATION WHICH MAY
BE PRODUCED WILL NOT BE HAZARDOUS AT A
DISTANCE SAFE FOR HIGH POTENTIAL
TESTING, IF THE TEST IS CONDUCTED AT THE
REC-OMMENDED VOLTAGE AND WITH THE
NORMAL OPEN CIRCUIT BREAKER GAP.
DO NOT APPLY VOLTAGE THAT IS HIGHER THAN
THE RECOMMENDED VALUE. DO NOT USE
CONTACT SEPARATION THAT IS LESS THAN
THE RECOMMENDED OPEN-POSITION BREAKER
CONTACT GAP.
This test of the vacuum interrupter will determine its
internal dielectric condition and vacuum integrity.
A vacuum integrity test is performed using an AC
high potential tester. A vacuum integrity test of the
inter-rupter is required to insure that no loss of
vacuum has occurred. With the breaker open,
individually check each interrupter by connecting the
hi-pot machine “Hot,” lead to the primary bushing and
the ground lead to the load side bushing. If the
machine has a center point ground, the connections
can be made either way. Apply 36 kV (rms) 60 Hz at
500 vps and hold for 10 seconds. If no breakdown
occurs, the interrupter is in acceptable condition.
After the high potential volt-age is removed,
discharge any electrical charge that may be present
through the internal ground of the test machine or by
a grounded cable to one of the phase bushing.
If a failure of a vacuum bottle should occur during the
integrity test, the test procedure should be reviewed
and the pole piece cleaned. GE failure rate for
vacuum bottles is 0.0007 per field unit. Note the
voltage level at failure on the first test, and retest the
phase pole piece. If the pole piece passes test, the
vacuum bottle is acceptable STOP.
If the test fails again but at a higher voltage level
than was observed in the first test, clean the pole
piece and retest. If a failure of the integrity test
occurs a third time, consider the vacuum bottle to
have lost vacuum and replace the complete pole
piece as described under Repair of Interrupter
Assembly
Although a AC high potential test is recommended for
Checking the vacuum integrity, a DC high potential
test can also be conducted on the vacuum
interrupters at 50 kV and held for 10 seconds with the
restrictions noted as follows.
No attempt should be made to try to compare the one
vacuum interrupter with another nor to correlate the
condition of any interrupter to low values of DC
leakage current. There is no significant correlation.
After the high potential voltage is removed, discharge
any electrical charge that may be retained.
CAUTION: MANY DC HIGH POTENTIAL MA-
CHINES ARE HALFWAVE RECTIFIERS. THIS
TYPE OF HIPOT TESTER MUST NOT BE USED
TO TEST VACUUM INTERRUPTERS. THE
CAPAC-ITANCE OF THE POWER/VAC BOTTLES
IS VERY LOW AND THE LEAKAGE IN THE
RECTIFIER AND ITS DC VOLTAGE MEASURING
EQUIPMENT IS SUCH THAT THE PULSE FROM
THE HALFWAVE RECTIFIER MAY BE IN THE
NEIGHBORHOOD OF 120 Kv WHEN THE
METER IS ACTUALLY READ-