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6.5 INSULATION
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.
6.6 INSULATION INTEGRITY CHECK
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
the test voltage is 15 kV RMS, 60 Hz, 27kV RMS for circuit breakers
rated 8.25 kV and 15 kV. 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 terminals of the circuit breaker. Connect
the remaining terminals 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.
SECONDARY CIRCUIT:
Isolate the motor by disconnecting the two motor leads from the
terminal block. Connect all points of the secondary disconnect
contact pins with a shooting wire. Connect this wire to the high
potential lead of the test machine. Ground the circuit breaker
frame. Starting with zero, increase the voltage to 1125 RMS, 60 Hz.
Maintain the voltage for one minute. Successful withstand indicates
satisfactory insulation strength of the secondary control circuit.
Remove the shooting wire and reconnect the motor leads.
6.7 PRIMARY CIRCUIT RESISTANCE CHECK
The main contacts of the VR-Series + circuit breaker are inside
the vacuum chamber where they remain clean and require no
maintenance at any time. Unlike most typical circuit breaker designs,
the VR-Series + design uses a highly reliable and unique flexible
clamp design that eliminates the need for lubrication and inspection
for wear.
The dc electrical resistance of the primary circuit may be calculated
by measuring the voltage drop across the circuit. This test should
be performed with a low voltage, direct current (dc) power supply
capable of delivering no less 100A dc.
To check the primary circuit resistance:
•
Remove the circuit breaker from the circuit breaker
•
compartment
Close the circuit breaker
•
Pass at least 100A dc from terminal to terminal of each pole
•
unit in the closed position
Measure the voltage drop across the terminals.
•
The resistance can be calculated from Ohm's Law and is expressed
in micro-ohms. Repeat for the remaining two poles.
The resistance should not exceed the factory test levels more than
200% as stated in IEEE C37 .09. Factory test levels are recorded
on the circuit breaker test form, which is included with the circuit
VR-Series
breaker. If measurements exceed 200%, contact the manufacturer.
Resistance conversion for Temperature
R
= R
(1 + (T
conversion
Factory
Field
R
=
Resistance correction for temperature based from the
conversion
factory resistance measurement.
R
=
Resistance measurement from the factory.
Factory
T
=
Temperature measurement in the field.
Field
T
=
Temperature measurement from the factory.
Factory
r =
Copper resistivity temperature coefficient.
r =
0.0039 Copper Resistivity Temperature Coefficient / Deg C
r =
0.002167 Copper Resistivity Temperature Coefficient / Deg F
6.8 VR-SERIES + CIRCUIT BREAKER ELEMENT MECHANISM
CHECK
Make a careful visual inspection of the mechanism for any loose
parts such as bolts, nuts, pins, rings, etc. Check for excessive wear
or damage to the circuit breaker components. Operate the circuit
breaker several times manually and electrically. Check the closing
and opening times to verify that they are in accordance with the
limits in Table 4.
6.8.1 CLOSURE™ TEST (50DHP-VR + Modtls)
Introductione: The CloSure™ Test is a simple yet extremely effective
means to determine and monitor the ability of the mechanism to
close the circuit breaker contacts fully. It provides a quantitative
measure of the extra energy available in terms of over travel in
inches to close the circuit breaker contacts to their full extent. It may
be used periodically to monitor the health of the mechanism.
Gtntral Informatione: The CloSure™ Test can be performed on all
VR-Series + circuit breakers. (Refer to Table 6.2.) If the CloSure™
travel obtained is as specified, the mechanism performance is
satisfactory. If the CloSure™ travel does not conform as shown in
Figure 6.14, contact Eaton's Electrical Services & Systems for further
information. (See Step 13).
m DANGER
DO NOT ATTEMPT TO INSTALL OR PERFORM MAINTENANCE OR TESTS ON
THE EQUIPMENT WHILE IT IS ENERGIZED. NEVER PUT YOUR HANDS NEAR
THE MECHANISM WHEN THE CIRCUIT BREAKER IS IN THE CHARGED OR
CLOSED POSITION. DEATH OR SEVERE PERSONAL INJURY CAN RESULT
FROM CONTACT WITH ENERGIZED EQUIPMENT. ALWAYS VERIFY THAT
NO VOLTAGE IS PRESENT BEFORE PROCEEDING WITH THE TASK, AND
ALWAYS FOLLOW GENERALLY ACCEPTED SAFETY PROCEDURES.
Saftty Prtcautionse: Read and understand these instructions before
attempting any maintenance, repair or testing on the circuit breaker.
The user is cautioned to observe all recommendations, warnings and
cautions relating to the safety of personnel and equipment.
N
otte:
Htaring prottction is rtcommtndtd as tht circuit brtaktr is
optntd and clostd.
The recommendations and information contained herein are based
on Eaton experience and judgment, but should not be considered to
be all-inclusive or covering every application or circumstance which
may arise. If further information is required, you should consult
Eaton's Electrical Services & Systems.
Ttsting Proctdurtse: Assuming that the circuit breaker is safely
removed from the circuit breaker compartment enclosure and
positioned in an area outside the arc fault boundary, follow this
procedure to perform the CloSure™ test. For further instructions on
removal of the circuit breaker from the circuit breaker compartment,
refer to the appropriate section of this manual.
Instruction Book
IB182917EN September 2018 www.eaton.com
DHP-VR
+
Replacement Circuit Breaker
- T
)r)
Factory
+
33
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