System information

™
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Masterpact™ NT and NW Universal Power Circuit Breakers
Accessories
46
05/2014
Micrologic Trip Unit Accessories
External Neutral Current Transformer (CT)
The sensor is installed on the neutral conductor for
neutral protection and metering and residual current
ground-fault protection for equipment.
NOTE: The rating of the external neutral current
transformer must be compatible with the rating of the
circuit breaker.
External Sensor for Source Ground-Return
(SGR) and Modified Differential Ground-Fault (MDGF) Protection
NOTE: MDGF and SGR are for use on circuit breakers with 400 A and higher sensors.
For SGR System: The sensor is installed around the connection of the transformer neutral point to
ground and connects to the Micrologic 6.0A, 6.0P or 6.0H trip units. SGR requires a modified
differential ground-fault (MDGF) sensor and MDGF interface module to connect to the trip unit.
For MDGF System: An MDGF sensor is installed on each phase and neutral of each circuit breaker
and connects to the Micrologic trip unit through an MDGF module. See MDGF Instruction Bulletin
48049-182.
Metering Current Transformers (CTs)
Metering current transformers are optional and are
mounted on the NW UL or ANSI cradle. They permit
connection to the standard metering device. All
metering transformers are accurate with the 0.3%
accuracy class, 5 A output ratio at full load (for example,
a 1600 A metering CT would send 5 A at the full load of
1600 A). A standard wiring harness is also included for
factory-installed MCTs. Not available for neutral pole on
a 4P circuit breaker. Not available on cradles with
ArcBlok™ technology.
Voltage Measurement Inputs
Voltage measurement inputs are required for power
measurements. As standard, the trip unit is supplied by internal
voltage measurement inputs placed on the bottom terminals of
the circuit breaker. On request, the internal voltage
measurement inputs may be replaced by an external source.
Sensor Plugs
Sensor plugs (standard) are used to set the sensor rating (I
n
) of the
circuit breaker, are field replaceable and are offered at 50–100% of
frame rating. For a complete list of available sensor plugs see
selection information in Section 7.
External Neutral Current
Transformer (CT)
Toroidal Current
Transformers
(CTs) for W-Frame
Circuit Breakers
Voltage
Measurement
Inputs
Sensor Plug