Trip
Shaft
Latch Not
Made Position
Latch
Check
Switch
NC
NO
C
Latch Made
Position
Trip
Actuator
Figure 3-17 Latch Check Switch Operation
As the breaker opens, a pin on the left pole unit shaft strikes
a vertical leg (reset arm) of the undervoltage tripping lever
and rotates it counterclockwise against its torsion spring.
Another arm on the tripping lever resets the roller latch and
moving core. A slight amount of overtravel on the trip latch
insures positive resetting under all conditions.
The undervoltage trip attachment is bolted in place in the
lower circuit breaker chassis. Always connect the undervolt-
age coil on the line side of the breaker unless the attach-
ment is equipped with a time delay device. In this case, the
time delay will delay tripping of the breaker long enough to
permit energization of the undervoltage coil from the load
side. Do not use an auxiliary switch contact in the undervolt-
age circuit.
3-10.8 Overcurrent Trip Switch
The overcurrent trip switch is optional on both manually and
power operated breakers. Its function is to provide a signal
to indicate that the breaker has tripped open by action of
the electronic trip unit due to phase or ground overcurrent.
Tripping by the trip plate, shunt trip device, undervoltage trip
device and other such methods does not cause it to operate.
Pole
Shaft
Breaker Closed
Position
Breaker Closed
U.V. Energized
Breaker Open
Position
Trip Bar
Breaker
Closed
Figure 3-18 Undervoltage Trip Attachment Operation
It is mounted on and operates from the trip actuator of the
breaker. Three standard contact arrangements are available:
(1) two normally open, (2) two normally closed, or (3) one
normally open and one normally closed. These are indepen-
dently wired to breaker secondary disconnect contacts.
Special units may have one additional contact.
The device is latch-type and must be manually reset by
means of a pushbutton mounted on the breaker front panel.
An electric reset type is available for remote operation (Fig-
ure 3-19).
3-11 Miscellaneous Details
3-11.1 Interference Interlock
A “Z” shaped bracket prevents a circuit breaker with an
insufficient interrupting rating or mismatched disconnects
from being inserted into the wrong compartment (Figure
3-14). The breaker mounted bracket has to properly key
with a bracket mounted on the compartment floor to permit
breaker insertion (Table 3.1). An interference interlock
bracket is standard on all drawout circuit breakers.
Effective July 2010
Instructional Book
IB694C694-03
27
eaton corporation
www.eaton.com
