Installation checks and
functional tests
The suggested procedure to engage the
racking mechanism is as follows:
1. The circuit breaker must be OPEN. (The
racking shroud cannot be moved if the
circuit breaker is CLOSED.)
2. Hold the socket-end of the crank in one
hand and the crank handle in the other
hand.
3. Place the socket over the end of the
racking-mechanism shaft. Align the
socket with the shoulder on the
racking-mechanism shaft.
Note:
If the socket is not aligned, the
socket will not be able to engage the
shoulder of the racking-mechanism shaft.
4. Once alignment is achieved, firmly
push the crank and socket assembly
toward the racking mechanism.
5. When properly engaged, the crank
should remain connected to the
racking mechanism. If the crank does
not remain in position, adjust the
spring plungers clockwise one-half
turn. This will increase the contact
pressure of the spring plunger.
6. To remove the crank, pull the assembly
off of the racking-mechanism shaft.
Note:
If the effort to rack the circuit
breaker increases considerably during
racking, or if turning of the racking crank
requires excessive force, stop racking
immediately. Do not try to force the
racking crank to rotate, or parts of the
circuit breaker or racking mechanism could
be damaged. Determine the source of the
problem and correct it before continuing
with racking.
Physical inspections
1. Verify the rating of the circuit breaker is
compatible with both the system and
the switchgear.
2. Perform a visual-damage check. Clean
the circuit breaker of all dust, dirt and
foreign material.
Manual-spring charging check
1. Insert the manual-spring charging
crank into the manual-charge handle
socket as shown in Figure 4. Turn the
crank clockwise (about 48 revolutions)
until the spring condition indicator
shows the closing spring is CHARGED.
2. Repeat the spring discharge check.
3. Verify the springs are DISCHARGED and
the circuit-breaker primary contacts are
OPEN by indicator positions.
As-found and vacuum-integrity check
tests
Perform and record the results of both the
as-found insulation test and the vacuum-
integrity check (dielectric) test. Procedures
for these tests are described in the
Maintenance section of this instruction
manual pages 40-52.
Automatic spring-charging check
Refer to the specific wiring information
and rating label for your circuit breaker to
determine the voltage required and where
the control-voltage signal should be
applied. Usually, spring-charging power is
connected to secondary-disconnect fingers
SD16 and SD15, closing control power to
SD13 and SD15 and tripping power to SD1
and SD2.
When control power is connected to the
type 38-3AH3 vacuum circuit breaker, the
closing springs should automatically
charge, if the racking crank is not engaged.
Figure 4: Manual charging of the
closing springs
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