Introduction
3
Figure 1.3
Operational Overview
1.3
SB Encased Systems Breaker
Siemens SB Encased Systems Breakers come in four (4) princi-
pal frame sizes with MAX Ratings ranging from 400 to 5000
amperes. The rating is determined by the current transformers
within the frame. All frames are rated for 100% continuous opera-
tion. Rated trip units are available for all SB Encased Systems
Breakers.
Trip units are fully field installable by authorized personnel. A
special rejection scheme is built into the frames and trip units to
prevent the installation of a trip unit into a frame for which it is not
intended.
The combinations of frame sizes and frame ampere ratings are
illustrated in
Table 1.1
.
Field interchangeable rating plugs are used to set the continuous
current rating of the circuit breaker. For a list of available rating
plugs, refer to
Table 2.2
on page 13.
The interrupting rating of the SB breaker is specified on the front
cover label and is further identified by the use of a “color bar” at
the top left of the breaker label.
Several short circuit interrupting ratings are available to meet spe-
cific applications. The interrupting ratings and short time ratings
are given in
Table 1.2
on page 4
.
The trip unit that may be used
with a specific circuit breaker is identified on the front cover label of
the breaker.
Decide
Act
Sense Current
P
N
Trip Breaker
Collect/Transmit Data
Set Off Alarm
I = 1427 A
I = 1375 A
I = 1415 A
A
B
C
V = 276 V
V = 278 V
V = 279 V
A
B
C
Frame Rating
2000 A
System
Status
System
Check
Tripped
Protective
Alarm
Meter
Rating Plug
I = 1600 A
r
ESC
Serial Port
Test Connector
Table 1.1
Breaker Frame Size and Rating Combinations
Breaker Frame Size(A)
Breaker Frame Ampere Rating
1200 400,
800,
1200
2000 1200,
1600,
2000
3200 2500,
3200
5000
2500, 3200, 4000, 5000
