Siemens Energy & Automation, Inc.
Bellefontaine, Ohio 43311 U.S.A.
Installation Instructions
Hazardous Voltage.
Will cause death or severe
injury.
Turn off and lock out all power supplying this
device before removing cover(s) or device
and while cover(s) are removed.
Wire connector shield no. NDTS must be
installed when wire connectors TA2K8750,
TA3P8750, TA4P8500, TA2N8750,
TA3N8750, OR TA4N8500 ARE USED.
Replace all covers and shields before power
supplying this device is turned on.
Page
5 of 6
Instantaneous
Pickup
xIr
NOTE:
Breaker contains an override at multiples
of the maximum continuous current rating. These
multiples are12.5 times for 600A - 800A breakers.
Ten (10) times for 1000A breakers and 8 times for
1200A breakers. Above these levels, the short time
delay is no longer operational, and the breaker will
trip instantaneously.
Adjustable Ground Fault (optional)
Pickup Ig = % In
Delay I
2
t @.5 In
Circuit breakers with the letter “G” included in the
catalog number have intergral equipment ground
fault protection. These circuit breakers have an
adjustment to set the Ground Fault Pickup current
(Ig) as a percentage of the Maximum Continuous
Current rating (In).
The pickup has a built in time delay. Three time
delays are available of 0.1, 0.2 or 0.4 seconds.
These are selected by using the appropriate area
of the setting. Below 50% Maximum Continuous
Current rating (In), the pickup delay has an I
2
t slope.
The ground fault option has two modes of opera-
tion. The mode is set by a switch on the bottom of
the trip unit with the settings identified as RESIDUAL
and GROUND RETURN. See Fig. 4 for switch lo-
cation.
RESIDUAL MODE (OUTGOING CIRCUIT METHOD)
—This is the standard position that the breaker is
set to when shipped from the factory. With the switch
in this position, the circuit breaker may be used on
3 phase 3 wire or, with the addition of an external
neutral sensing transformer, on 3 phase 4 wire sys-
tems.
GROUND RETURN SETTING (GROUND
RETURN METHOD) — This setting may only be
used for service disconnects or separately derived
systems. With the switch in this position, the circuit
breaker may be used on 3 phase 3 wire and 3 phase
4 wire systems. An external sensing transformer,
which is installed on the main bonding jumper, is
required for this method. See Neutral Sensing
Transformer section for more information.
Instantaneous Trip Switch
xIr
The adjustable instantaneous trip switch allows se-
lection of a tripping point from 2 to 40 times the
ampere rating. The MAX setting sets the instanta-
neous pickup to the override level (see note be-
low). The diagram below illustrates the possible set-
tings for this switch.
Ground Fault
Pickup
Ig = %In
I
2
t
Delay
@.5 In
.1s
.2s
.4s
The adjustable ground fault pickup and delay switch
allows for the selection of ground fault pickup at
various percentages of the maximum ampere rat-
ing (% In), with an I
2
t delay @.5x In of .1, .2, or .4
seconds. The diagram below illustrates the possible
settings for this switch.
MAX
40
Released Production, B v1, Dec 18, 1998
Released Production, C v1, Apr 18, 2011
