27
Instructional Leaflet
IB2C12063H03
Effective March 2012
Instructions for Installation, Operation and
Maintenance of Magnum SB Insulated Case
Low Voltage Power Circuit Breakers
EATON CORPORATION
www.eaton.com
Toroidal
Sensor
Figure 36. Replaceable Current Sensors Shown with Bottom
Adapters and Cover Plate Removed
Table 6. Magnum SB Current Sensors and Matching Rating Plugs
Current Rating in Amperes
200
800
2500
250
1000
3000
300
1200
4000
400
1600
5000
600
2000
Trip Actuator
The trip actuator is a small cylindrically shaped electromagnetic
device which acts mechanically to trip the circuit breaker
(
Figure 33
) . 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, allowing the spring loaded
rod to act mechanically . The device is reset when the circuit
breaker opens .
Mechanical Trip Flag
A red, pop out mechanical trip indicator is an optional Magnum
SB feature . It is located above the trip unit on the breaker’s
front faceplate (
Figure 34
) . 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 .
Making Current Release
All Magnum SB Double-wide 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 .
Fixed Instantaneous Non-Adjustable Setting
Magnum SB 800-3000 ampere breakers through 100kA AIC
rating have a fixed instantaneous non-adjustable setting . This
value is set at 18 x In symmetrical rms . In is defined by the
current sensor and rating plug combination . This setting is
always active, regardless of the instantaneous setting .
High Instantaneous Trip
The high instantaneous trip option is installed on all SBSE
breakers . On the Magnum SBSE standard frame circuit
breakers (800-2000A) this rating is set at 30kA . On the
Magnum SBSE Double-wide frame circuit breakers (2500-
5000A) this rating is set at 50kA . In general, the high
instantaneous trip is comprised of three small air core sensors,
one in each phase, which produce a signal and transmits it
back to the trip unit when the rating of the circuit breaker is
exceeded . The result is an instantaneous trip by the circuit
breaker . This high instantaneous trip option permits the
Magnum SBSE circuit breakers to be applied where a 150kA
fault is possible, while selectivity up to the high instantaneous
trip value is maintained .