Mode of trip and status information
All trip units have a tricolored light-emitting diode (LED), labeled
STATUS that could light green, red or orange. The LED will blink
green approximately once each second to indicate the trip unit
is operating normally. This Status LED will blink at a faster rate
if the Digitrip is in a pick-up or overload condition.
The Digitrip has the ability to detect a problem with nonvolatile
memory or if the trip actuator coil is an open circuit, or if there
is a circuit breaker mechanism problem. Depending upon the
state and the status of power to the trip unit when a problem is
detected, the Status LED will light red or flash red or orange.
There are LEDs on the face of the trip units (for INST, LONG,
SHORT, and GROUND) that flash red to indicate the cause or
trip mode for an automatic trip operation. A battery located in
the Frame Module maintains the trip indication until the Reset/
Battery Test button is pushed. The battery is good if the LED
lights green when the Battery Check button is pushed (see
Section 9: Trip unit battery).
ote:
N
The trip unit provides all protection functions regardless of the
status of the battery. The battery is only needed to maintain the cause
of trip indication during a power loss condition.
Trip Unit Installation
The Digitrip trip units are designed as a field replaceable
unit. To mount the Digitrip trip unit align it with the two guide
grooves of the Series NRX circuit breaker. Keep it parallel with
the receiving, molded deck plate. Press the unit into the circuit
breaker until the trip unit seats firmly into the receiving housing
and the two latching tabs click into place.
Figure 4. Trip Unit Installation on a Frame Module
Rating Plug Installation
Insert the rating plug into the cavity on the right side of the trip
unit. Wiggle the plug slightly to help align the pins on the plug
with the sockets in the cavity. The plug should engage with a
slight insertion force when it is approximately 3/16-inch (4 mm)
above the Digitrip. When this occurs, tighten the mounting
screw to its stop positions. 4 turns should be sufficient.
•
CAUTION
IF A RATING PLUG IS NOT INSTALLED IN THE TRIP UNIT, THE UNIT
WILL INITIATE A TRIP WHEN IT IS ENERGIZED.
Figure 5. Installation of the Rating Plug into the Trip Unit
ote:
N
Rating plugs are keyed to circuit breaker frame groups. If the
wrong rating plug is used it will not engage and properly tighten down
to the circuit breaker frame, see Section 10: Frame ratings and rating
plugs for the tables of available rating plugs.
•
CAUTION
DO NOT FORCE THE RATING PLUG INTO THE CAVITY.
Use a 1/8-inch (3 mm) wide screwdriver to tighten the
mounting screw and secure the plug and the trip unit to the
circuit breaker.
•
CAUTION
THE RATING PLUG SCREW SHOULD BE TIGHTENED ONLY UNTIL IT
STOPS. DO NOT USE A LARGE SCREWDRIVER. A 1/8-INCH (3 MM)
WIDE SCREWDRIVER BLADE IS ADEQUATE.
Trip unit/rating plug removal
To remove the rating plug from the trip unit, use a 1/8-inch (3
mm) wide screwdriver to loosen the screw. It will take about
four turns to release it. Pry up the top or bottom side lips of the
rating plug to pull it away from the trip unit.
To remove the trip unit from the circuit breaker’s Frame Rating
Module, break the factory seal, deflect the two locking tabs,
and pull to release the unit from the frame module mounting
plate. Pull the unit to disengage the molded, 24-pin connector
from the frame module printed circuit board. (See
Figure 6
and
Figure 7.
)
Effective September 2013
Instructional Leaflet IL01301064E
Operating Manual for Series NRX
Digitrip Trip Units 1150 / 1150i
14
EATON
www.eaton.com
