Figure 4-12d shows the REMOVE position. Here the inter-
lock cam stops with the shutter interlock pin blocked. The
shutter stays down and the breaker stays tripped when the
levering crank is removed. The breaker is held trip-free and
cannot be closed. In addition, another interlock, described
later, stops the close-release latch from being released.
4-5.6 Spring Discharge Interlock
The spring discharge interlock operates the close-release
latch as the breaker is moved out beyond the TEST position.
This causes a trip-free operation of the closing mechanism
because it occurs while the levering crank is still on the
worm shaft, and the closing springs are charged on a power
operated breaker. This is because the levering crank is still
being used to move the breaker in the final part of its travel
to the DISCONNECT position. The trip plate is still pushed in
and the breaker is trip-free.
Figure 4-13 shows the essential parts of the spring discharge
interlock. Figures 4-13a and b show the levering device in
the -remove position. The interlock plate has two horizontal
pins (7 and 8) extending from it, as shown in Figure 4-13. The
upper one is designate Pin “A” and the other Pin “B”. In lever-
ing the breaker out to the REMOVE position, the levering
shaft turns counterclockwise until the levering device arms
are horizontal to the rear (Figures 4-13a and b). As it rotates,
the close bar cam is rotated counterclockwise by Pin “B” to
the CLOSE position. This releases the spring release latch
through the linkage shown in Figure 4-13. This results in a
trip-free operation of the breaker if the closing springs are
charged. It happens because the levering crank has the trip
plate held in the “Trip” position. If the breaker is manually
operated, levering out can be stopped at the TEST position.
Remove the levering crank and (1) close the breaker and (2)
trip the breaker. This will discharge the springs so that, when
the REMOVE position is reached, there will not be a trip-free
operation. The close bar is merely pulled into the “Close”
position.
4-5.7 Connected Breaker Manual Close Interlock
The purpose of this interlock is to provide a choice between
being able to close the breaker by pushing on the close bar
and not being able to, with the breaker in the CONNECT po-
sition. Referring to Figure 4-13a, the interlock plate assembly
is keyed loosely to the levering device shaft by a drive pin.
If the interlock screw is omitted, the interlock plate can be
rotated freely on the shaft about 10 degrees. This is because
the wide slot is considerably wider than the drive pin. If the
interlock screw is in place in the narrow slot, the interlock
plate has practically no play and is forced to rotate exactly as
much as the levering device rotates.
Figure 4-13c shows the standard arrangement without the
interlock screw, with the levering device arms in the CON-
NECT position. Note that there is a clearance between the
back of the hook and Pin “A”. This permits the close bar to be
pushed to the “Close” position and the breaker to close.
All parts in Figure 4-13d are in the same position as in Figure
4-13c, except that the interlock screw is placed in the nar-
row slot. This forces the interlock plate to rotate about 10
degrees further than in Figure 4-13c. In this case, there is
almost no clearance between Pin “A” and the back of the
hook. Consequently, the close bar cannot be pushed to the
“Close” position. The breaker can, however, be remotely
closed by supplying control voltage to the spring release coil
through a control switch or other circuit making device.
4-5.8 Electric Lockout Equipped Breaker
Manually operated breakers can be equipped for electric
lockout. This means that closing an unenergized circuit is
prevented. This can be the main circuit or any other desired
circuit. It is accomplished by making it impossible for the
required spring release device to release the spring release
latch unless the monitored circuit is energized. The spring
release coil (SR) is wired through the contact on the auxiliary
switch, a front panel closing pushbutton switch, and to the
terminals of the circuit being monitored. When the moni-
tored circuit is energized properly, the breaker can be closed
through the panel pushbutton switch, provided that the clos-
ing springs are charged.
As an additional safeguard against undesired closing under
this electric lockout condition, all such breakers are provided
with the interlock screw described in the previous paragraph
(4-5.7). This prevents hand closing of the breaker in the CON-
NECT position.
4-5.9 Closed Breaker Interlock
Figure 4-14 shows how operating of the spring release latch
is prevented when the breaker is already closed. The close
bar is connected to the spring release latch by a link and bell
crank. The link is pivoted on the lower end of the close bar
cam by a pin. As the close bar is pushed, the pin and latch
link move to the right along with the lower end of the cam.
The lower end of the link
Effective July 2010
Instructional Book
IB694C694-03
44
eaton corporation
www.eaton.com
