Specifications

Operating Instructions
Part Three – Monitoring the Electronic Trip Unit
20
Trip Unit Test and Monitoring Functions
Siemens Electronic Trip Unit is equipped with three standard
test and monitoring functions to aid the user in the installation
and operation of the SB breaker.
System Check Indicator
The System Check Indicator is a green LED that blinks approx-
imately once every three seconds when the microprocessor is
correctly cycling through its protection routines.
The trip unit derives its operating power from the phase currents
in the SB breaker.The phase current required to operate the trip
unit is approximately 20% of the MAX rating. If the microproces-
sor is not correctly cycling through its protection routines, the
phase current is below 20% (MAX rating), the LED will not light.
Trip Status
NOTE: A Trip Status Reset Button is provided on newer
version trip units.
The trip Query button and Trip Status indicator lights provide
the user the means for determining what type of fault caused
the trip unit to trip the breaker. Fault indicators are provided for:
O.L. — Overload or Long Time Fault
S.T. — Short Time Fault
S.C. — Short Circuit or Instantaneous Fault
G.F. — Ground Fault
When a fault occurs, the fault information is stored in the trip
unit by latching the appropriate red LED fault indicator to the
“On” position.When the Query button is depressed, the
latched fault indicator will light.The electrical power to the
indicators is automatically stored in the trip unit, eliminating
the need for a battery pack. A hole is provided in the transpar-
ent cover to allow the user access to the Query button.
NOTE: During trip unit power up, the S.C. fault indicator
LED will latch, providing a means to check that the cir-
cuitry is correctly operating. In case of a fault, the correct
indicator will be latched to the fault position.The indica-
tor circuitry will latch the most recent event. Newer ver-
sion trip inits feature a Trip Status LED Reset Button.
Integral Test Modes
The integral test function enables the user to “exercise” the
trip unit electronics, the magnetic latch, and the breaker
mechanism.The purpose of the integral test function is to
provide the user an easy means to conduct a “go/no go”
type test before bringing the breaker online. After the breaker
has been brought on-line, it may be used during routine
inspection and maintenance.
Both phase fault current protection and ground fault current
protection may be tested.The integral ground fault test func-
tion tests the circuit breaker’s ground fault protection system
in accordance with NEC Article 230-95(c).
Electrical power to operate the integral test function is provid-
ed internally, if the breaker is closed and the phase currents
are greater than 20% of the MAX rating, or by a plug-in power
source (see Accessories section).
The user may execute the test function in either a “no trip”
mode, which will test only the trip unit electronics, or a “trip”
mode, which will also test the magnetic latch and breaker
mechanism.The execution of the integral test function in both
the “no trip”and “trip”modes is based on the settings of the
long time delay and ground fault delay adjustments.Therefore,
the Phase Test will take several seconds to execute and the
Ground Fault Test will appear to be nearly instantaneous.To
execute a test function in the ”no trip” mode, depress the
appropriate pushbutton test switch, Phase or GF. As the trip
unit is performing the test, the Testing Indicator will light. If
the trip unit successfully passes the test, the Pass Indicator
will light. If the Pass Indicator does not light after the Testing
Indicator indicates that the test is complete, a more extensive
test should be run with Siemens TS-31 Universal Test Kit
(see Accessories).
SYSTEM
CHECK
Continuous
SIEMENS
n
I =%I
r
100
50
60
65
70
75
80
90
95
Rating Plug
l
n
= 2000A
85
Phase
G.F.
Trip
APM
TEST
TS31
TestingPass
Query
Trip
Status
O.L. S.T.
S.C. G.F.
CAUTION
Before doing a “Trip” test on a SB Breaker
which is “Closed” and in service,caution
should be taken to evaluate effects on
downstream loads. Breaker will open during
test, resulting in a disruption of service.