Operations; Selecting A Circuit Breaker For An Application; Cable Or Bus Size - Factor A; Table 6.4. Entelliguard G Non-Automatic Switch Close, Latch, And Withstand Ratings, Ul489 Listed - GE EntelliGuard G Application Manual

DET-653C
24-May-12
Table 6.4. EntelliGuard G Non-Automatic Switch Close,
Latch, and Withstand Ratings, UL489 Listed
Envelope Amps
1 800 - 2000
2 800-3000
3 4000 - 6000
EntelliGuard G circuit breakers are provided with values that
are high relative to the circuit breaker's load carrying
capacity. The trip system provides a type of instantaneous
protection called a Making Current Release (MCR) to provide
more sensitive protection when closing. Should the trip
system measure higher current than the MCR setting, it is
very likely that the circuit breaker has been closed on a
bolted fault, or low impedance, arcing fault. If that is the
case, the MCR instantaneous will provide very fast
protection, minimizing damage and hazard.

Operations

EntelliGuard G circuit breakers are designed to provide
long life, even in operationally difficult environments.
However, different standards have different ways of
measuring and qualifying circuit breaker operations,
hence slightly different numbers may apply to similar
circuit breakers when defined within the context of
different standards. Tables 6.5 and 6.6 describe the
endurance parameters for the circuit breaker family.
Table 6.5. Operational Ratings, UL 489 Circuit Breakers
Envelope Frame
800-1600A
1
2000A
800A
2 1600-3000A
3000-4000A
3 5000A
6000A
76
Type Close and Latch
Rating (kA)
N 42
M 65
B 100
12500 10000 7500
12500 7500 5000
12500 5000 5000
5000 5000 5000
5000 3000 2000
5000 2000 1500
5000 1500 1000
EntelliGuard
Table 6.6. Operational Ratings, UL1066/ANSI Circuit
Breakers
Envelope Frame
800-1600A
1
2000A
800A
2
1600-3200A
3200- 4000A
3
5000A
Per industry standards, operations are listed based on no
maintenance during the testing. However, if some
maintenance is done of some of the current carrying parts
and arc chute, then over 20,000 electrical and mechanical
operations are possible.

Selecting a Circuit Breaker for an Application

There are six application factors to consider in selecting
current rating for a circuit breaker. These are:
1. Size of the cable or bus used in the line and load
connections.
2. Actual installed ambient temperature.
3. System operating frequency.
4. Altitude of the installation.
5. Type of loading of the protected circuit.
6. Design safety factor.
The following simple relationship combines these six
application factors into a single equation:
CR = IA x A x B x C x D x E x F
CR Required circuit breaker current rating, amps
IA Actual load current, amps
A Cable or bus sizing factor
B Ambient temperature rating factor
C Frequency rating factor
D Altitude rating factor
E Load class rating factor
F Safety factor
Cable or Bus Size – Factor A
The thermal design of a circuit breaker takes into account
the ability of the line and load cables or buses to act as
heat sinks. For UL489 Listed circuit breakers, UL has
assigned specific cable or bus sizes for each current
rating. Generally, these assignments are coordinated with
specific conductor temperature ratings. When using a
conductor with an increased temperature rating, the
higher rating decreases both the cross-sectional area and
its ability to conduct heat from the circuit breaker. If an
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® G Circuit Breaker Application Guide
Section 6. Application Data
12500 10000
12500 7500
12500 5000
5000 5000
5000 3000
5000 2000
7500
5000
5000
5000
2000
1500