Effective 7/1/2003
Page 27
I.L. 70C1037H04
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
.
An alternative test setup is shown in Fig. 5.4. This three
pole in series hookup should be employed when a low
Ground Pickup setting is to be tested like 0.24x and 0.3x
and if Aux power to Digitrip can not be provided. The Test
Circuit does provide a net Residual ground current excita-
tion of “1”. Two of the phases cancel each other out as far
as ground fault but now the Digitrip is provided with three
pole power up current simulating three phase power.
Figure 5.3 Connection Details for Conducting Single Phase
Current Tests with the Breaker Removed from
the Cell
Suitable
Conductors
Low-Voltage
ac Current
Source
Primary
Disconnect
Stabs-
When Drawout
A
B
C
Polarity &
Identification
Figure 5.4 Alternate Connection Details using three poles
to develope a Ground Fault Condition.
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).
