rotate the trip latch counterclockwise, but the trip latch is
kept from rotating by overlap of the latch surface of the trip
shaft. A very small rotation of the trip shaft thus releases the
trip latch to rotate counterclockwise to the position shown
in Figure 4-7a. The enlarged views of the trip shaft and trip
latch tip in Figure 4-7e show in detail the rotation of the trip
shaft for release of the trip latch. The entire linkage collapses
under the force of the main contacts and comes to rest with
the breaker open (Figure 4-7a). Note that the trip latch is still
in the released position (not reset).
If the breaker stands open with springs charged as in Figure
4-7b, and if the trip shaft is held in the rotated or trip posi-
tion, an attempt to close will result in a trip-free operation.
This is so because with the trip shaft in the trip position,
there is no restraint on the trip latch. Therefore, no force is
applied to the main link to close the breaker.
Although certain interlocking operations may or will result in
this trip-free type of operation, it causes some extra shock
on the mechanism parts. Therefore, trip-free operations
should be avoided.
The trip shaft can be rotated to trip the breaker in a number
of ways:
1. Breaker Trip Plate (Figure 3-3) — Pushing the trip plate will
trip the breaker. This item has a tab which pushes against
a pin on the trip shaft, which applies a direct rotating force
on the shaft in the tripping direction (Figure 4-11).
2. Shunt Trip Device (Refer to Paragraph 3-10.4)
3. Trip Actuator (Refer to Paragraph 3-7.3)
4. Compartment Door Trip Flap — If the breaker is in the
CONNECTED position in its compartment, pushing the
door mounted trip flap will trip the breaker. It operates
through a sliding link and lever fastened to the drawout
cradle floor. When pushed, it engages the compartment
trip lever, extending from the bottom of the breaker, to
cause tripping (Figure 3-16).
5. Undervoltage Trip Attachment (Refer to Paragraph 3-10.7)
Indicator Index Tab
Front Panel
Levering Worm Shaft
Levering Worm
Indicator Pivot Pin
Traveling Stop Nut
Traveling Stop Nut Clamp
Indicator Lever
Levering Worm Gear
Levering Shaft
Figure 4-10 Drawout Unit Position Indicator
Effective July 2010
Instructional Book
IB694C694-03
39
eaton corporation
www.eaton.com
