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Instruction Book
IB182012EN March 2017 www.eaton.com
50DH-VR-50AXU / 50XU / 75U / 75ARU - 600 / 1200A
Replacement Circuit Breaker
5.3.2 50-DH-VR-50 XU/75ARU (REAR RACKING)
a. Place the circuit breaker in the withdrawn position out of the cell.
The racking handle is not required for this position and the racking
system interlocks are not automatic outside the cell. The circuit
breaker can be mechanically operated in this position if the position
mode indicator reads “TEST/OPERATE”. Extreme care should be
exercised to avoid inadvertent operation and possible injury or
equipment damage.
WARNING
THE CIRCUIT BREAKER CAN BE OPERATED WHEN WITHDRAWN FROM
THE CELL AND EXTREME CARE SHOULD BE EXERCISED TO AVOID
INADVERTENT OPERATION AND POSSIBLE INJURY AND/OR EQUIPMENT
DAMAGE.
b. From the withdrawn position, ensure the circuit breaker is open
and the mechanism is completely discharge. Engage the racking
handle and rotate the racking handle counter-clockwise as far as
possible and align the circuit breaker wheels with the guide rails of
the cell. (See Figure 5.6)
c. Check that the closing spring status indicator reads “OPEN”.
Manually trip, close, an trip the circuit breaker as needed to obtain
this status.
d. Push the circuit breaker into the cell until all the wheels
are on the cell floor. The racking arm rollers will not meet the
guide slots and the shutters have not begun to open. This is the
“DISCONNECT” position.
WARNING
THE SHUTTER WILL RISE POSSIBLY EXPOSING HIGH VOLTAGE BEFORE
THE RACKING ARM ROLLERS ENGAGE THE GUIDE SLOTS. EXTREME CARE
SHOULD BE EXERCISED TO AVOID POSSIBLE INJURY OR EQUIPMENT
DAMAGE.
e. Continue pushing the circuit breaker into the cell. The shutters
will start to rise. The circuit breaker will travel approximately eight
(8) inches from the “DISCONNECT” position before the racking arm
rollers meet the guide slots.
f. To rack the circuit breaker further into the cell, engage the racking
handle and rotate the racking handle clockwise approximately 1
turn. The position mode indicator (Figure Set 3.3) will reflect “TEST/
OPERATE”. In the “TEST” position, the circuit breaker can be closed
and tripped manually and electrically, thus allowing maintenance test
or checks. To operate the circuit breaker electrically, the secondary
disconnect must be engaged at this time. Release the secondary
disconnect slider by pulling the catch pin and pushing the slider
toward the rear several inches. The slider is located on the lower left
area of the circuit breaker frame. Push on the front side flat surface
of the slider until the secondary disconnect can be felt to be fully
engaged with the secondary disconnect of the switchgear.
g. To advance from the “TEST” position, continue turning the
racking handle clockwise. The circuit breaker will travel approximately
4.25 inches. Towards the end of travel, the racking torque will
increase due to the additional resistance of the primary disconnect
contact fingers engaging the cell copper. The circuit breaker will be
considered in the “CONNECT” position when the position indicator
reads “TEST/OPERATE”. This indicates that the trip linkage is
released and the circuit breaker is now ready for service.
5.4 REMOVAL PROCEDURE
5.4.1 50-DH-VR-50 AXU/75U (FRONT RACKING)
a. To remove the circuit breaker from the cell, it must be in the open
position. Ensure the circuit breaker is open and engage the racking
handle. Move the circuit breaker out by rotating the racking handle
counter-clockwise. The circuit breaker will start coming out of the
cell before the secondary disconnect or primary disconnects are
disconnected. The circuit breaker will be in a non-operable mode
and will be prevented from closing if any attempt to close it is made
in the intermediate position. The shutters will close after the main
primary disconnects have cleared, isolating the circuit breaker from
the power source. Continue racking out until the position mode
indicator shows “TEST/OPERATE” and the shutter indicator shows
closed. The circuit breaker is in the “TEST” position and the trip
mechanism is released, allowing the circuit breaker to be operated
either electrically or mechanically. If you desire to electrically open
or close the circuit breaker in the “TEST” position, the secondary
disconnect must be reengaged and the racking handle removed.
b. To remove the circuit breaker from the “TEST” position to the
“DISCONNECT”, the circuit breaker must be tripped if closed, the
racking handle reinserted, and the secondary disconnect should be
disengaged. Rotate the racking handle counter-clockwise until the
racking mechanism movement is halted by the racking mechanism
stop. When moving out of the “TEST” position, a close signal will
combine with a trip signal from the interlock cam to force a trip-free
condition. This will cause the charging springs to discharge leaving
the circuit breaker in the open position. The racking handle should
be removed at this point. The circuit breaker is ready to be removed
from the cell.
c. To remove the circuit breaker from the disconnected to the
withdrawn position, the circuit breaker is pulled manually by the
pull handle located immediately above the position mode indicator.
The racking handle is not required between the withdrawn and
disconnected positions.
If it is desired to leave the circuit breaker in the cell instead of
moving it from the test position to the completely withdrawn
position, rotate the racking handle counter-clockwise one rotation.
This will place the circuit breaker in a “trip-free” mode but will not
discharge the closing springs. This prevents unnecessary wear to the
circuit breaker mechanism.
5.4.2 50-DH-VR-50 XU/75ARU (REAR RACKING)
a. To remove the circuit breaker from the cell, it must be in the open
position. Ensure the circuit breaker is open and engage the racking
handle. Move the circuit breaker out by rotating the racking handle
counter-clockwise. The circuit breaker will start coming out of the
cell before the secondary disconnect or primary disconnects are
disconnected. The circuit breaker will be in a non-operable mode
and will be prevented from closing if any attempt to close it is
made in the intermediate position. Continue racking out the circuit
breaker until the position mode indicator reads “TEST/OPERATE”.
The circuit breaker is in the “TEST” position and the trip mechanism
is released, allowing the circuit breaker to be operated either
electrically or mechanically. If you desire to electrically open or close
the circuit breaker in the “TEST” position, the secondary disconnect
must be reengaged and the racking handle removed.
WARNING
THE SHUTTERS ARE OPEN IN THE “TEST” POSITION. CARE SHOULD BE
EXERCISED WHEN OPERATING THE CIRCUIT BREAKER MECHANICALLY
OR ELECTRICALLY OR POSSIBLE INJURY AND/OR EQUIPMENT DAMAGE
COULD RESULT.
b. To remove the circuit breaker from the “TEST” position, continue
turning the racking handle in a counter-clockwise direction until a
mechanical stop is achieved. Using the handle located above the
position mode indicator, pull the circuit breaker towards the front of
the cell until the shutters fully close isolating the circuit breaker from
the power source. This is the “DISCONNECT” position.
c. To remove the circuit breaker from the cell, continue pulling
the circuit breaker towards the front of the cell using the handle
provided. The circuit breaker will encounter no stops and will be able
to be pulled completely clear of the cell. The racking handle is not
required.