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Instruction Leaflet IL0131154EN
Effective August 2021
Section 1: Neutral current sensor installation
Ground fault trip units detect ground fault current through residual
sensing. If the system neutral is grounded and residual ground fault
is desired, but no phase to neutral loads are used, a neutral current
sensor is not necessary.
If the system neutral is grounded and phase to neutral loads are
used, then the neutral current sensor (see Figure 1) must be used
to account for this load in the residual ground fault sensing.
Source
N
X2*
X1*
Neutral sensor
(CT or Rog coil)
Load
*CT connections facing the load
Figure 1. Neutral current sensor application
Magnum circuit breakers with PXR trip units come with the option
of connecting either a current transformer (CT) or a Rogowski coil
as the neutral sensor. Whichever current sensor is selected, it is
connected to the same two secondary terminals. Refer to
Figure 1 for connections. Only the current sensors described in this
document should be used with Magnum PXR trip units.
2
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Source
L C R
N. N
N
C17 C16
Load
Refer to Figure 2 for instructions on how to use the trip unit display
to select the type of sensor that you are using. If no sensor is used,
the CT selection should be made (this is the factory default setting).
If a Rogowski coil is selected and no coil is connected, false current
readings and possibly trips will occur.
From Main Menu:
Edit Settings [PW] Neutral Sensor [Rogowski/CT]
Figure 2. Current sensor selection
Rogowski primary connections should be made by connecting the
source neutral connection on the side or terminal where the dot is
placed. For the CT there is no dot on the unit. The source should be
routed through the side opposite the secondary terminals. Refer to
Figures 3 & 4 for dimensional and labeling details.
Table 1. Catalog number and use details
Frame
Application
Catalog#
Standard or
Rog bus bar
NRMPN
narrow
Standard or
CT
MSCNCT
narrow
Neutral current sensors
Magnum PXR ACB trip units
Ratings
Where Used
Details
All
Figure 3
All
Figure 4
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