Circuit Breaker Closing Mechanism - Eaton DS-206S series Instructions Manual

Instruction Booklet IB 33-790-1J
Effective November 2010

5.1.5 Circuit Breaker Closing Mechanism

This mechanism is of the general variety of mechanically
trip-free mechanisms. This means that the breaker can
be opened or tripped free from the closing mechanism at
any point in its closing stroke. It also means that if the trip
latch is held in the "trip" position while the spring release
latch is released, the closing springs will make a trip-free
operation but the breaker contacts will not close or move
appreciably toward the closed-position.
Based on this construction, the breaker close and trip
linkage can have four steady state conditions. The
arrangements of the basic close and trip linkage for these
four conditions are shown in Figures 22a, 22b, 22c, and
22d as follows:
Figure 22a Breaker Open, Springs Discharged, Trip
Latch Not Reset;
Figure 22b Breaker Open, Springs Charged, Trip Latch
Reset;
Figure 22c Breaker Closed, Springs Discharged; and
Figure 22d Breaker Closed, Springs Charged.
The angular position of the close cam in Figure 22a cor-
responds to the angular position of the drive plates and
Fig. 23 Shunt Trip Details Showing Trip Shaft Adjustment.
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Instructions for Low Voltage Power
Circuit Breakers Types DS and DSL
closing spring crank arms shown in Figure 16b. The trip
latch is in the tripped position and it will reset to the
latched position at the end of the spring charging stroke.
The closing springs are charged by counterclockwise
rotation of the ratchet and drive plates until the close cam
stop roller meets the spring release latch, as shown in
Figure 22b.
Note in Figure 22b also that the lower end of the main
drive link, with the main roller, has swung upward and
toward the left, pushing the trip latch constraining link so
as to rotate the trip latch back to the reset position. This
occurs at the same time that the spring charge is com-
plete and just before the close cam stop roller strikes the
spring release latch. The position of the cam in Figure
22b corresponds to the position of the drive plates in Fig-
ure 16a spring charged, breaker open.
The breaker is now ready to be closed. Closing is started
by counterclockwise rotation of the spring release latch.
Refer again to Figure 22b. This removes the hold on the
close cam stop roller, and allows the force of the closing
springs to rotate the close cam counterclockwise and
close the breaker. The linkage is then in the position
shown in Figure 22c. The close cam has rotated about
180 degrees.