22
Interrupter/Operator Description
A spring loaded latch arm (9) rises to engage the latch
face, which is an integral feature of the cylindrical
assembly. The latch arm (9) is held in this position by the
vertical lever (10), which is pulled to the supporting
position by the electromagnet. The vertical lever is pivoted
(11) by the electromagnet (12) against the force
developed by an extension spring (13), which constantly
attempts to pull the vertical lever (10) into a position
which releases the stored energy torsion spring.
The latch arm supported by the vertical lever retained in
position by the electromagnet will retain the stored energy
state until the electromagnet senses a loss of trip supply
voltage. When the supply voltage falls to a level 30 to 60
percent of nominal, the electromagnet releases the vertical
lever, the latch arm descends and the cylindrical assembly
rotates displacing the trip shaft. Latching is established at
85% nominal voltage.
Interlocks
There are two interlocks which prevent certain unsafe
operating conditions. They are the rating interlock and the
trip-free interlock.
Figure 29:
Undervoltage Trip Option.
Trip-Free Interlock
Figure 30
shows the devices providing the trip-free inter-
lock function. The purpose of the trip-free interlock is to
hold the circuit circuit breaker operating mechanism
mechanically and electrically trip free whenever the circuit
breaker is between the Test and Connected positions
within the switchgear enclosure. This interlock ensures
that the circuit breaker primary contacts can only be closed
when in the Connect position, or the Test position, or out
of the switchgear cell.
Rating Interlock
Figure 30
shows the rating interlock interference plates
mounted on the circuit breaker frame. The circuit breaker
interference plates are complemented by matching plates
located in the cubicle.
The interference plates (rating interlocks) test the circuit
breaker voltage, continuous current, interrupting and
momentary ratings and will not allow circuit breaker inser-
tion unless they match or exceed the cell rating.
Circuit Breaker Frame
The frame of the GMI circuit breaker contains several
important devices and features deserving of special atten-
tion. These are the ground disconnect, the four racking
wheels and four handling wheels.