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Vehicle Description
As the push rod rises, its "mushroom" headed append-
age, within the circuit breaker mechanism enclosure,
causes the "interlock" levers to rotate, elevating the "trip
free push rod and cam". This cam encounters the "trip
latch lever", and after typically 8 to 12mm (0.3 to 0.5 inches)
of motion forces the mechanism, through the "trip latch
lever", and coupled "trip latch" to an opened and "trip
free" condition shown in Figure 2.
Continued full CCW rotation of the interlock bell crank
causes the plunger to clear the cubicle rail allowing the
"open trip free breaker" to be moved from the connected
position.
The lower interlock bell crank is returned to the plunger
engaged position, fully clockwise, by the action of double
torsion springs at each end of the bell crank. It is stopped
and maintained in the position which ensures full plunger
engagement by a spring pin of sufficient length at the top
of the plunger which straddles the guide bar and guiding
channel.
The circuit breaker may be pad locked in an "open trip-
free" state. Provision has been made for looping a padlock
through the "racking release handle" and a stationary
cover mounted angle. The position of the racking release
handle at the point of padlock hole alignment ensures the
circuit breaker is trip-free yet the plunger engages the rail
preventing breaker movement.
Plunger Position Mechanical Interlock
In order to prevent the motor charging circuit from "making
and breaking" as the circuit breaker and cubicle
secondaries make or break physical contact, an electrical
switch is provided. This switch is mounted within the
connection box, and is operated by a lever attached to a
member on the interlock bell crank. The switch is adjusted
to ensure the circuit breaker charging circuit is made up
before the racking plunger achieves full engagement.
Typically, the plunger will be 51mm (2 inches) off the floor
when this switch makes the circuit.
Automatic Closing Spring Release
Reference: Figures 2 & 3
The automatic closing spring release feature is provided
to ensure all spring energy has been discharged in the
mechanism prior to the circuit breaker removal from the
cubicle. The opening springs are discharged prior to the
circuit breaker release for racking, and since automatic
closing spring discharge occurs while the circuit breaker
is trip free and its charging circuit is opened, we can be
assured all spring energy has been released as the circuit
breaker exits the cubicle.
Reference to Figure 3 reveals the essential elements of
this system. As the circuit breaker exits the cubicle, the
roller encounters an actuating angle in the floor of the cu-
bicle. As the roller strikes the angle it must rise, and this
Figure 3.
Details of Automatic Closing Spring Discharge System
change in elevation is amplified through a lever and ful-
crum arrangement located above the roller. Movement of
the roller from a typical free height of 65mm (2.56 inches)
to 74mm (2.91 inches) must produce approximately 20mm
(0.75 inches) of vertical motion at the "spring dump tube".
Reference to Figure 2 shows the spring dump tube tele-
scoping the trip free push rod, and thus the spring dump
tube is able to move against the mechanism interlock le-
vers independently of the trip free function. As the dump
roller approaches the actuating angle the trip free rod will
be elevated, holding the mechanism trip free. When the
roller strikes the actuating angle, it overtakes the trip free
push rod and moves beyond the trip free position. This
action is allowed because the "mushroom" tip at the top
of the trip push rod is not attached to this push rod, but
simply "floats" above it, captured by the mechanisms in-
terlocking levers.
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