Magnum
1812.900A
27
External neutral current sensors are also available for
customer installation. The additional sensor is not
supplied with the circuit breaker and must be ordered
separately. They are wired to the trip unit through the
secondary contacts of the circuit breaker.
Refer to Table 3-2 for a tabulation of the available current
sensor ratings.
Figure 3-19: Replaceable Current Sensors Shown with
Bottom Adapters and Cover Plate Removed
1. Toroidal Sensor
Table 3-2: Magnum Current Sensors and Matching Rating
Plugs
Current Rating in Amperes
200 1000 3150
250 1200 3200
300 1250 4000
400 1600 5000
600 2000 6300
630 2500
800 3000
3.6.4 Trip
actuator
The trip actuator is a small cylindrically shaped
electromagnetic device which acts mechanically to trip
the circuit breaker in response to a signal from the trip
unit. In general, it is comprised of a permanent magnet, a
spring loaded rod to produce the mechanical tripping, and
a lever for resetting the actuator after tripping occurs.
The electronic trip unit provides a pulse which
counteracts the effect of the permanent magnet,
releasing the spring loaded rod to act mechanically. The
device is reset when the circuit breaker opens.
3.6.5 Mechanical
trip
flag
A red, pop out mechanical trip indicator is an optional
Magnum feature. It is located above the trip unit on the
breaker’s front faceplate (Figure 3-17). It operates by
releasing and popping out any time the circuit breaker
trips due to to an overcurrent condition. Note that the
mechanical trip indicator will not prevent the breaker
from being reclosed. The indicator is reset manually by
pushing it back in. If the indicator is not reset the circuit
breaker will operate normally, but future mechanical trip
indication will be lost.
An optional overcurrent trip switch (bell alarm) that
operates off the position of the mechanical trip indicator
is also available. The switch is reset when the trip
indicator is reset.
On optional Digitrip models with LED cause-of-trip
indicators, these indicators should also be reset (by
pushing momentarily) after the cause of the fault has
been diagnosed; this will preserve the internal battery.
On trip units equipped for communication the LED reset
function can be performed remotely using INCOM
commands.
3.6.6 Making
current
release
All Magnum circuit breaker trip units have a making
current release function. This safety feature prevents the
circuit breaker from being closed and latched on a faulted
circuit. The non-adjustable release is preset at a peak
instantaneous current of 25 x In; this corresponds to an
rms current of 11 x In with maximum asymmetry.
The making current release is enabled only for the first 2
cycles following a circuit breaker closing operation. The
making current release will trip the circuit breaker
instantaneously, release the mechanical (pop-out)
indicator and flash the instantaneous LED trip indicator, if
so equipped.
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