SECTION 1 4-MicroVersaTrip® Plus and MicroVersaTrip® PM Trip Units
1 4.6 NEUTRAL CURRENT SENSORS
CAUTION:
Neutral current sensors are required for three
phase, four-wire systems. When the trip unit is connected
to a three-phase, three-wire system, the neutral sensor
terminals are left open. Do not short any neural current
sensor termi nals in a three-phase, three-wire system, as
this could result in damage to or malfunction of the
electrical system.
Fig. 1 1 8 shows the neutral sensor. The neural sensor is
required when integral g round fault protection is used on
single phase-three wire or three phase-four wire systems.
It is inserted into the neutral conductor and therefore is
separately mounted in the cable or bus compartment.
The outputs of the phase sensors and neutral sensor
are connected to a programmer circuit which sums these
values. The total value will remain zero as long as there is
no ground current flowing.
1 4.7 RATING PLUG REMOVAL AND RE
PLACEMENT
CAUTION:
Removal of the rating plug while the breaker
is carrying current reduces the breaker's current-carrying
capacity to approximately 25% of the current sensor
rating.
Interchangeable rating p lugs are removed with a Rating
Plug Extractor, Catalog No. TRTOOL. (Suitable equiva
lents are commercially available as "integrated circuit
(DIP) extractors.") Grasp the rating plug tabs with the
extractor and pull the plug out. Be sure to g rab the tabs
and not the front cover of the rating plug, or the plug may
be damaged .
Rejection features are provided on all rating plugs to
prevent application mismatches. Never force a rating
plug into place. Refer to Table 1 6 to find the appropriate
rating plugs for each sensor rating and breaker frame.
The neutral sensor is an electrical duplicate of the phase
If a replacement rating plug has a d ifferent rating than
sensor. Therefore, when phase sensors are changed, the the plug that was removed, follow the appropriate setup
neutral sensor must be correspondingly be changed .
procedure G EH-5891 A to enter the new rating.
FIG. 1 18 TYPICAL NEUTRAL SENSOR
Do not attem pt to use a rating plug from a Spectra RMS
breaker or a MicroVersaTrip® Plus or M icroVersaTrip"'
PM Trip Unit.
TABLE 1 6
Sensor
Plug
Breaker
Cat. No.
Rating, Amps
Rating
Frames
TR481 50
1 50
TR48200
200
TR48225
400
225
AKR30 ,
TR48250
250
AKR30H
TR48300
300
TR48400
400
TR88300
300
TR88400
400
AKR30,
TR88450
450
AKR30H,
TR88500
800
500
AKR50S,
TR88600
600
AKR50H
TR88700
700
TR88800
800
TR1 68600
600
TR1 68800
800
TR1 681 000
1 600
1 000
AKR50 ,
TR1 681 1 00
1 1 00
AKR50H
TR1 681 200
1 200
TR1 681 600
1 600
TR208750
750
TR208800
800
TR2081 000
1 000
TR2081 200
2000
1 200
AKRT50H
TR2081 500
1 500
TR2081 600
1 600
TR2082000
2000
81
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