Effective 11/2003
Page 32
I.L. 66A7535H02
performing Long Delay, Short Delay, and Ground Fault
functional tests. The Cutler-Hammer-approved test kit is
listed below.
Model
Test Kit
Digitrip
1150V
Test Kit (140D481G02R, 140D481G02RR,
140D481G03, or G04) with Test Kit Adapter
8779C02G04
The test port is located on the front left-hand corner of the
DT1150V units
(See Figure 1.1).
To access the port,
remove the plexiglass cover from the front of the circuit
breaker. Using a small screwdriver, gently pry up on the
test port cover to remove this item.
The test kit authorized by Cutler-Hammer for use with the
Digitrip units plugs into the test port of the unit and
provides a secondary injection test that simulates the C-H
Type-V current sensors. Existing test kits, styles
140D481G02R, 140D481G02RR, 140D481G03 or G04,
along with the Test Kit Adapter 8779C02G04, can be used
to test the trip unit and breaker.
5.3 Performance Testing of Digitrip 1150V Trip Units
5.3.1 General
The complete circuit breaker should be tested after sensor
wiring is completed. The AVO Multi-Amp
®
model MS-2 or
equivalent current source can be used to perform this test
(See Figure 5.1)
.
5.3.2 Testing using MS-2 Multi AMP
®
Tester
The portable (33lb/15kg) AVO Multi AMP
®
tester, model
MS-2 can be used to check out Digitrip 1150V.
5.3.2.1 General Description of Testing with MS-2
There are two levels of testing that can be done. A primary
or secondary injection test can be done. The primary
injection test is good for verifying both CH Type-V current
sensor polarity and hookup through the circuit breaker’s
secondary contacts and into the Digitrip 1150V trip unit.
This is a complete system checkout and is strongly
recommended after initial setup and before energizing of
the gear. Although the MS-2 source is limited to 600
amperes (momentary), it can verify that the trip unit powers
up properly and perform a ground fault trip of the circuit
breaker. This testing at the primary injection level is able to
verify that the breaker’s response to each primary phase
current is correct. The secondary injection current source
is able to deliver up to 5x (1 ampere is 1 per unit) into the
breaker’s secondary contacts. This can produce a 300%
overload test and a 400% Short Time or Instantaneous
test.
The following extra components are desirable additions for
the testing.
1. For the primary injection testing, three separate flexable
(welding type) cables (#2 AWG or larger) and each about
3’ (.914m) long, are required to be fabricated. Connectors,
with tabs, need to be attached on each end to connect to
the tester’s terminal studs. The flat tab extension will also
provide a surface to attached to the gear’s bus conductors
using C-clamps. A typical connector style would be an
ILSCO style SLS125.
2. For secondary injection tests, a separate True RMS
ammeter with a “peak hold” feature is required
(See Figure
5.5).
The built in meter of the MS-2 tester is not True RMS
and does not provide an accurate measurement of the
secondary injection current. This is because of the trip
unit’s “chopper” power supply. The peak hold feature will
hold the trip current level when an auxilary switch from the
circuit breaker is wired back to the tester’s terminals
(white posts) labeled
Contacts
.
3. Also when performing low current secondary injection
tests (less than 2 Amperes) it is desirable to insert an
additional 25 ohm impedance (resistor or inductor) rated at
25 or 50 watts in series with the
5A
terminal post. This will
provide proper impedance for the “chopper” and is useful in
stablizing the current
(See Figure 5.5).
4. Auxilary Power Module (
See Figure 5.1)
5.3.2.2 Primary Injection Testing
Preliminary hookup:
a. Connect an Aux Switch or unused unused circuit
breaker pole to the
Contacts
input terrminals of the MS-2
current source to hold current ramp value level and to stop
the timer.
b. Set Digitrip 1150V
Ground Setting
to “0.4” and remove (if
any) jumpers connected on secondary points B-6, B-7
(See Figure 1.6).
c. Connect one end of the primary current cables to the
240A
and
Common
posts of the MS-2 test source.
Connect the other ends to the line and load side of the
breaker’s left pole(Phase “A”). This will provide a primary
current through CH Type-V current sensor for the test.
d. Set MS-2 built-in meter to
750A
scale.
