41
5.
Release the breaker release latch and pull the circuit
breaker out from the DISCONNECT position. The breaker
is now free to be rolled out on the two extension rails
using the handles on the front of the circuit breaker.
6.
Remove the breaker from the two extension rails using the
approved Siemens breaker lifting device (see
Figures 40
and
41
), or a lifting sling (see
Figure 48
) and a suitable crane.
7.
Lift the two extension rails and withdraw them from the
switchgear.
Type GMI circuit breakers weigh between 385 and 575
pounds (175-261kg), depending upon their ratings. The breaker
can be moved using a properly rated crane and lift sling. A lift
sling can be attached to the breaker, and then used to hoist the
circuit breaker vertically clear of the extension rails. When clear,
remove the rails and lower the circuit breaker to the floor.
Racking Crank Engagement Procedure
A crank for racking the drawout circuit breaker is provided as a
standard accessory. Racking of a circuit breaker can be
accomplished with the drawout compartment front door open
or through a small opening (or window) in the front door, with
the door closed.
The racking crank consists of an offset handle with a custom
socket assembly welded to the opposite end. The socket end
of the crank is designed to engage the square shoulder of the
racking mechanism shaft and remain engaged during racking
by means of two spring plungers located 180 degrees from
each other. The spring plungers operate in a manner similar to
the retainers on an ordinary mechanic’s socket wrench.
The portion of the racking mechanism shaft which is visible is
cylindrical, and the square shoulder of the racking mechanism
shaft is hidden by a shroud until the engagement procedure
starts. The square socket end of the crank will only engage the
square portion of the shaft if it is aligned properly.
The suggested procedure to engage the racking mechanism is
as follows:
1.
The breaker must be open. (The racking shroud cannot be
moved if the breaker is closed).
2.
Hold the socket end of the crank in one hand and the
crank handle in the other hand. Refer to
Figure 42.
3.
Place the socket over the end of the racking mechanism
shaft. Align the spring plunger of 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 socket (square) must be aligned with the
square 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, due to the spring plungers. 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, simply 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
the racking.
Circuit Breaker Position
WARNING
Heavy weight.
Can cause death, serious injury, or property
damage.
Always use extension rails to remove or install cir-
cuit breaker in cells not installed at floor level.
WARNING
Heavy weight.
Can cause death, serious injury, or property
damage.
Never transport a circuit breaker on a lift truck or
other lifting device with the circuit breaker in the
raised position.
