Eaton Digitrip 520 - Page 28

28
Instructional Leaflet IL70C1037H05
Effective October 2009
Digitrip models 520, 520i; and 520M, 520Mi,
520MC, 520MCi trip units for use only in
Magnum and Magnum DS circuit breakers
EATON CORPORATION www.eaton.com
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 40. 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 41) or through a
breaker pole and the neutral that employs a neutral sensor.
Figure 41. Connection Details for Conducting Single-Phase
Current Tests with the Breaker Removed from the Cell
A B C
Suitable Conductors
Low Voltage
AC Current
Source
Primary Disconnect
Stabs—When Drawout
Polarity and Identification
A B C
Suitable Conductors
Low Voltage
AC Current
Source
Primary Disconnect
Stabs—When Drawout
Polarity and
Identification
Shorting
Conductors
An alternative test setup is shown in Figure 42. 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 auxiliary power to Digitrip
can not be provided. The test circuit does provide a net residual
ground current excitation 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 42. Alternate Connection Details Using Three Poles to
Develop a Ground Fault Condition
m CAUTION
RESTORE ALL TEMPORARY CONNECTIONS MADE FOR THE PURPOSE
OF CONDUCTING TESTS TO PROPER OPERATING CONDITIONS BEFORE
RETURNING THE BREAKER TO SERVICE.
Record the test results on the test form provided with the
equipment (see Figure 46).
Suitable
Conductors
Low Voltage
AC Current
Source
Polarity and
Identification
Primary Disconnect Stabs
When Drawout
A B C