25
Instruction Book IB019009EN November 2017 www.eaton.com
AK-2-25, AK-2A-25, & AK-3A-25 LV-VSR
Breaker-To-Motor Starter Conversion
6.3.5 INSPECTION AFTER SHORT CIRCUIT
The magnitude of a short circuit may exceed the damage threshold
of the vacuum bottle on the V201 contactor. After a short circuit,
the unit should be examined for any apparent physical damage, or
deformation of conductor bars. If there is any evidence of severe
stress, it is recommended that the unit be replaced. If the over-
travel has changed significantly (from the last inspection) on one or
more bottles, the unit should be replaced.
A dielectric test may be performed at 1760V (80% of factory test
level) See Section 6.6. A dielectric test would not by itself confirm
that the unit should be returned to service after a fault. Vacuum
Integrity is to be performed at 5.5kV ac RMS per section 6.4.
However, if there is no physical evidence of stress, and if the over-
travel exceeds the 0.020 inch minimum, the bottles can then be
dielectrically tested as outlined in this manual. If physical stress,
over-travel, and dielectric are satisfactory, it is reasonable to return
the unit to service after a fault and after unit has been properly
cleaned.
6.4 VACUUM INTERRUPTER INTEGRITY TEST
Vacuum interrupters used in LV-VSR are highly reliable interrupting
contactors. Satisfactory performance of these devices is dependent
upon the integrity of the vacuum in the interrupter and the internal
dielectric strength. Both of these parameters can be readily checked
by a one minute ac high potential test. (See Table 6.1) During this
test, the following warning must be observed:
Only use an ac high potential test set. A dc high potential test may
result inaccurate test results.
WARNING
APPLYING ABNORMALLY HIGH VOLTAGE ACROSS A PAIR OF CONTACTS
IN VACUUM MAY PRODUCE X-RADIATION. THE RADIATION MAY
INCREASE WITH THE INCREASE IN VOLTAGE AND/OR DECREASE IN
CONTACT SPACING. X-RADIATION PRODUCED DURING THIS TEST
WITH RECOMMENDED VOLTAGE AND NORMAL CONTACT SPACING
IS EXTREMELY LOW AND WELL BELOW MAXIMUM PERMITTED BY
STANDARDS. HOWEVER, AS A PRECAUTIONARY MEASURE AGAINST
POSSIBILITY OF APPLICATION OF HIGHER THAN RECOMMENDED VOLTAGE
AND/OR BELOW NORMAL CONTACT SPACING, IT IS RECOMMENDED THAT
ALL OPERATING PERSONNEL STAND AT LEAST ONE METER AWAY IN
FRONT OF THE LV-VSR.
1. Conduct test with the LV-VSR open and securely placed on a
workbench or suitable surface.
2. Short the Current Transformers and the secondary block
connections to ground.
3. Connect all top primary studs (bars) together and the high
potential machine lead.
4. Connect all bottom studs together. Do not ground them to
the LV-VSR frame, connect the high potential ground to the
bottom studs.
5. Start the machine at zero potential, increase to appropriate
test voltage and maintain for one minute.
6. Successful withstand indicates that all interrupters have
satisfactory vacuum level. If there is a breakdown, the contactor
should be replaced before placing the LV-VSR in service.
7. After the high potential is removed, discharge any electrical
charge that may be retained, particularly from the center shield
of vacuum interrupters. To avoid any ambiguity in the ac high
potential test due to leakage or displacement (capacitive)
current, the test unit should have sufficient volt-ampere capacity.
It is recommended that the equipment be capable of delivering
25 milliamperes for one minute.
8. Remove ALL shorting wire on Current Transformers and
secondary block before placing unit back into service.
WARNING
FAILURE TO REMOVE ALL SHORTING WIRE FROM THE CURRENT
TRANSFORMERS AND SECONDARY CONNECTIONS MAY CAUSE INJURIES
AND EQUIPMENT DAMAGE.
DC HIGH POTENTIAL TESTS ARE NOT RECOMMENDED ON VACUUM
INTERRUPTER ASSEMBLIES.
6.5 INSULATION
In LV-VSRs, insulation maintenance primarily consists of keeping
all insulating surfaces clean. This can be done by wiping off all
insulating surfaces with a dry lint free cloth. In case there is any
tightly adhering dirt that will not come off by wiping, it can be
removed with a mild solvent or distilled water. Be sure that the
surfaces are dry before placing the LV-VSR in service. If a solvent is
required to cut dirt, use isopropyl alcohol. Secondary control wiring
requires inspection for tightness of all connections and damage to
insulation.
6.6 INSULATION INTEGRITY CHECK
PRIMARY CIRCUIT:
The integrity of primary insulation may be checked by the ac high
potential test. The test voltage is 1760 V RMS, 60 Hz. Conduct the
test as follows:
1. Conduct test with the LV-VSR open and securely placed on a
workbench or suitable surface.
2. Ground the LV-VSR frame.
3. Short the Current Transformers connections to ground.
4. Close the Contactor on the LV-VSR. Control power will be
needed to close the Contactor.
5. Connect the high potential lead of the test machine to one of
the phases of the LV-VSR.
6. Connect the remaining two phases and LV-VSR frame to
ground.
7. Start the test machine with output potential at zero and
increase to the test voltage. Maintain the test voltage for one
minute.
8. Repeat for the remaining phases. Successful withstand
indicates satisfactory insulation strength of the primary circuit.
9. Disconnect the control power from the LV-VSR.
10. After the control power has been removed and disconnected
from the LV-VSR. Short all of the secondary connections
together and to the frame.
11. Connect the high potential lead of the test machine to one of
the poles of the LV-VSR.
12. Connect the remaining poles and LV-VSR frame to ground.
13. Start the test machine with output potential at zero and
increase to the test voltage. Maintain the test voltage for one
minute.
14. Repeat for the remaining poles. Successful withstand
indicates satisfactory insulation strength of the primary circuit.
15. Remove ALL shorting wire on the current transformers and
secondary block before placing unit back in to service.
WARNING
FAILURE TO REMOVE ALL SHORTING WIRE FROM CURRENT
TRANSFORMERS AND SECONDARY CONNECTIONS MAY CAUSE INJURIES
AND EQUIPMENT DAMAGE.
