Primary Circuit:
The integrity of primary insulation may be checked by the ac high potential
test. The test voltage depends upon the maximum rated voltage of the
circuit breaker. For the circuit breakers rated 4.76 kV, 8.25 kV and 15 kV
the test voltages are 15 kV, 27 kV and 27 kV RMS, 60 Hz respectively.
Conduct the test as follows:
Close the circuit breaker. Connect the high potential lead of the test
machine to one of the poles of the circuit breaker. Connect the remaining
poles and circuit breaker frame to ground. Start the machine with output
potential at zero and increase to the test voltage. Maintain the test voltage
for one minute. Repeat for the remaining poles. Successful withstand
indicates satisfactory insulation strength of the primary circuit.
Open the circuit breaker. Connect the high potential lead of the test
machine to one of the poles of the circuit breaker. Connect the remaining
poles and circuit breaker frame to ground. Start the machine with output
potential at zero and increase to the test voltage. Maintain the test voltage
for one minute. Repeat for the remaining poles. Successful withstand
indicates satisfactory insulation strength of the primary circuit.
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 CIRCUIT
BREAKER.
Insulation Integrity Test
otee:
N
Roll over each high potential test diagram configuration above to see the
correct lead connection to the equipment.
otee:
N
The ground connection can be attached to the plated frame.
otee:
N
The secondary disconnect must be grounded during test.
In VR-Series circuit breakers, 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 or dry paper towel.
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. But be sure that the surfaces
are dry before placing the circuit breaker in service. If
a solvent is required to cut dirt, use Isopropyl Alcohol
or commercial equivalent. Secondary control wiring
requires inspection for tightness of all connections and
damage to insulation.
Power Frequency Withstand Voltage Testing Configuration: Open Circuit
Power Frequency Withstand Voltage Testing Configuration: Closed Circuit
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS
Lead
C B A
G/R
Lead
OS Lead
= Output Signal Lead
G/R Lead
= Ground / Return Lead
5
EATON
| Visual Instruction Booklet Essentials | DST-2-VR - 18WR Element | May 2017
