Effective 2/2/2001
Page 26
I.L. 70C1037H03
WARNING
PERSONAL INJURY CAN OCCUR WHEN WORKING ON
POWER SYSTEMS. ALWAYS TURN OFF POWER
SUPPLYING BREAKER BEFORE CONDUCTING TESTS.
TEST OUT OF THE CELL, IF POSSIBLE. THERE IS A
HAZARD OF ELECTRICAL SHOCK OR BURN WHEN-
EVER WORKING IN OR AROUND ELECTRICAL EQUIP-
MENT.
Verify the grounding points of the system using high-
voltage testers and resistance bridges to ensure that
ground paths do not exist that could bypass the sensors.
Use a low-voltage (0 to 24 volt), high-current, ac source to
apply a test current of 125 percent of the Digitrip unit pick-
up setting through one phase of the circuit breaker. This
should cause the breaker to trip in less than 1 second and
operate the alarm indicator, if one is supplied. Reset the
breaker and the alarm indicator. Repeat the test on the
other two phases
(See Figure 5.2).
Apply the same current as described above through one
phase of the breaker, returning through the neutral sensor.
The breaker should not trip, and the alarm indicator, if one
is supplied, should not operate. Repeat the test on the
other two phases.
Figure 5.2 Connection Details for Conducting Single Pole,
Single Phase Current Tests with the Breaker
Removed from the Cell
Apply the same current as described above through any
two phases of the breaker. The breaker should not trip, and
the alarm indicator,
if one is supplied,
should not operate.
Repeat the test using the other two combinations of
breaker phases
(See Figure 5.3)
or through a breaker pole
and the neutral that employs a neutral sensor
.
Figure 5.3 Connection Details for Conducting Single Phase
Current Tests with the Breaker Removed from
the Cell
CAUTION
RESTORE ALL TEMPORARY CONNECTIONS MADE
FOR THE PURPOSE OF CONDUCTING TESTS TO
PROPER OPERATING CONDITIONS BEFORE RETURN-
ING THE BREAKER TO SERVICE.
Record the test results on the test form provided with the
equipment
(See Figure 8.3).
6.0 TRIP UNIT BATTERY
6.1 General
The battery plays no part in the protection function of the
trip unit.
As indicated in Figure 3.1, the battery is provided to
maintain the red LED indication of the Cause of Trip in the
Digitrip 520 family of trip units. The battery is located under
the rating plug door. A battery check pushbutton and a
green Battery Check LED are also provided in the 520
family of trip units.
6.2 Battery Check
The battery is a long-life, lithium, camera-type unit. Check
the status of the battery at any time by pressing the
Battery Check pushbutton and observing the green LED. If
