IB131006EN
Page 48
Effective 07/2017
Secondary disconnect pins with 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 vac 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 motor leads.
6-8 PRIMARY CIRCUIT RESISTANCE CHECK
Since the main contacts are inside the vacuum
chamber, they remain clean and require no
maintenance at any time. Unlike many typical circuit
breaker designs, VCP-W breakers do not have sliding
contacts at the moving stem either. Instead they use a
highly reliable and unique flexible clamp design that
eliminates the need for lubrication and inspection for
wear.
If desired, the DC resistance of the primary circuit may
be measured as follows: close the circuit breaker, pass
at least 100 amps DC current through the circuit
breaker. With a low resistance instrument, measure
resistance across the studs on the circuit breaker side of
the disconnects for each pole. The resistance should not
exceed the values shown in Table
6.3.
Table 6.3 Typical Resistance Measurements
Rated Continuous
Current (amperes)
Resistance
(microohms)
1200
2000
3000
60
40
20
6-9 MECHANISM CHECK
Make a careful visual inspection of the mechanism for
any loose parts such as bolts, nuts, pins and rings.
Check for excessive wear or damage to the circuit
breaker components. Operate the circuit breaker sever-
al times manually and electrically. Check the closing and
opening times to verify that they are in accordance with
the limits in Table
5.2.
6-9.1 CLOSURE
™
TEST
Introduction:
The CloSure
TM
Test is a simple yet
extremely effective means to determine and monitor the
ability of the mechanism to close the breaker contacts
fully. It provides a quantitative measure of the extra
energy available in terms of over travel in inches to
close the breaker contacts to their full extent. It maybe
used periodically to monitor the
health
of the
mechanism.
At times, circuit breakers are called upon to operate
MOC switches (mechanism operated control switches)
that place extra load upon the closing mechanism of the
circuit breaker. If this load is excessive, it can prevent
the circuit breaker from closing fully. In such a case, it is
important to determine that the circuit breaker will close
fully. The CloSure
TM
Test provides this assurance.
General Information:
The CloSure
TM
Test can be per-
formed on the VCP-W, VCP-WR, VCPW-ND, DHP-VR,
W-VACR, and W-VAC lines of vacuum circuit breakers
Refer to Table
6.4
a for list of circuit breakers. If
theCloSure
TM
travel obtained is as specified, the
mechanism performance is satisfactory. If the CloSure
TM
travel does not conform as shown in Figure
6-12,
con-
tact Eaton for further information. (See Step
13
).
WARNING
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
Figure 6-5 Status Indicators (“A” shows the contact
Status indication and “B” and spring indication)
(Some breakers will not have the escutcheon that is
shown).
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