Vehicle Description
5
Circuit Breaker in Disconnect/Test Position (Refer to Figure 4)
Note: Figures 1, 2, and 3 pictorially represent a 5kV-350MVA
type GER circuit breaker. While the associated parts
required to perform the trip-free/spring dump function vary
in style and mounting among the various circuit breaker
ratings available, the function achieved is identical on all
type GER circuit breaker ratings.
Figure 1 is a partial representation of the circuit breaker in
the Disconnect/Test position, with the circuit breaker
resting on the top of the cubicle guide rails. Note: the
Disconnect/Test position on the type GER circuit breaker
is the same, and is the location achieved when inserting
the circuit breaker fully into the cubicle to the racking
position.
Note that in this position, the trip-free roller resides in the
lower cavity of the cubicle mounted moveable cam, and
that successful operation is dependent on the free rotation
of the trip-free roller.
The enlarged view of the circuit breaker operator in Figure
1 indicates that the circuit breaker is open, with closing
springs discharged.
In this condition, parts relating to the closing and spring
charging are not engaged, as is indicated by the location
of pawl roller, latching pawl, pawl and pawl roller. Note
also that the trip pushed cam, trip-free pushrod, interlock
levers, motor cutoff switch are in their lowest position.
It is recommended that the trip-free/spring dump interlock
be tested while the circuit breaker resides in the Disconnect/
Test position. Follow the procedure below to verify the
function of the trip-free/spring dump interlock:
1. On a de-energized bus, with the circuit breaker in the
Disconnect/Test position, manually charge the circuit
breaker’s closing springs, and bring the circuit breaker
to a CLOSED condition.
2. With the circuit breaker closed and the springs charged,
attempt to rack the circuit breaker by pulling the
elevating mechanism handle toward you.
3. Actuation of the elevating mechanism handle should
displace the trip-free roller counter-clockwise out of the
lower cavity of the cubicle mounted stationary cam. The
displacement of the trip-free roller should result in the
Figure 1. Trip-Free/Spring Dump Interlock (Circuit Breaker in Disconnect/Test Position)
