Rockwell Automation 140U N-Frame Circuti Breakers Instruction Leaflet for N-Frame Circuit Breakers - Manual

40752-093(1) Effective 5/02
DO NOT ATTEMPT TO INSTALL OR PERFORM MAIN-
TENANCE ON EQUIPMENT WHILE ENERGIZED.
DEATH, SEVERE PERSONAL INJURY, OR SUBSTAN-
TIAL PROPERTY DAMAGE CAN RESULT FROM CON-
TACT WITH ENERGIZED EQUIPMENT. ALWAYS
VERIFY THAT NO VOLTAGE IS PRESENT BEFORE
PROCEEDING WITH THE TASK, AND ALWAYS FOL-
LOW GENERALLY ACCEPTED SAFETY PROCE-
DURES.
ALLEN-BRADLEY IS NOT LIABLE FOR THE MISAP-
PLICATION OR MISINSTALLATION OF ITS PROD-
UCTS.
The user is cautioned to observe all recommendations,
warnings, and cautions relating to the safety of personnel
and equipment as well as all general and local health and
safety laws, codes, and procedures.
The recommendations and information contained herein
are based on Allen-Bradley experience and judgement,
but should not be considered to be all-inclusive or cover-
ing every application or circumstance which may arise. If
any questions arise, contact Allen-Bradley for further
information or instruction.
1. INTRODUCTION
The N-frame circuit breaker (Fig. 1-1), is a
600 VAC maximum rated device, with an integral
trip unit and interchangeable Rating Plug. Two
continuous current ratings are available 400-800
Amp and 600-1200 Amp. Refer to table 1-1 for available
trip units and table 1-2 for available rating plugs.
Fig. 1-1 N-frame Circuit Breaker
The N-Frame Trip Units are AC only devices that
employ microprocessor based technology that provides
true RMS current sensing means for proper correlation
with thermal characteristics of conductors and equip-
ment. The primary function of the Trip Unit is circuit pro-
tection. This is achieved by analyzing the secondary
current signals received from the circuit breaker current
sensors and initiating trip signals to the circuit breaker
shunt trip when pre-set current levels and time delay set-
tings are exceeded. Low level ground fault protection with
an adjustable time delay is supplied when appropriate trip
types are selected.
In open air at 40°C, an N-frame circuit breaker unit will
carry continuously up to 1200 amperes without
exceeding a 50°C rise at the terminals.
The calibration of the trip unit is insensitive to ambient
temperatures over a range of -20° to +55°C. However, the
trip unit contains thermal temperature protective circuitry
that initiates a trip operation for self-protection if the inter-
nal ambient temperature at the printed circuit board
(PCB) reaches approximately 90°C. For ambient condi-
tions above 40°C, derating of the circuit breaker should
be considered to avoid exceeding a safe terminal temper-
WARNING
N-Frame Circuti Breakers
Instruction Leaflet for N-Frame Circuit Breakers
Bul. 140U