36
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
Appendix B: Troubleshooting guide
Symptom Probable Cause Possible Solution(s) References
Unit Status LED is not blinking Current through breaker is <25% of
sensor rating
No problem, Status LED will not operate with breaker currents <25%
of sensor rating
Trip unit is malfunctioning Replace trip unit
Unit Status LED is steady on Light loading No problem, Status LED will not flash until 25% of sensor rating See Section 3 Note
Trip unit is malfunctioning Replace trip unit
As soon as current starts to flow through the
breaker, it trips and the Instantaneous Trip LED
comes on
Rating plug is not installed or is loose Install rating plug and/or check for loose connections
Rating plug is open internally Replace rating plug
Trip unit is malfunctioning Replace trip unit
LED does not come on when Battery Check
button is pressed or Cause of Trip does not light
after a trip via Digitrip
Battery installed backwards. Install correctly
Dead battery. Replace battery
Trip unit is malfunctioning Replace trip unit
Breaker trips on ground fault There actually is a ground fault Find location of the fault
On four-wire residual systems, the
neutral current sensor may not have the
correct ratio or be properly connected
Check connections at terminals B-4 and B-5, check that the neutral
current sensor ratio matches the breaker, check that the connections
from the neutral current sensor to the breaker are not reversed, check
B-6, B-7 for correct programming of jumper
See Section 2 Notes
Trip unit is malfunctioning Replace trip unit
High inrush phase currents may cause
fictitious ground pickup momentarily
Connect Zout to Zin jumper to provide some time delay, see Caution in
Section 3
Breaker trips too rapidly on ground fault or short
delay (zone selective interlocking not used)
Connection from Zout to Zin is missing. Make connections B-8 to B-9 Refer to Appendix A
Trip unit settings are not correct Change settings
Trip unit is malfunctioning Replace trip unit
Breaker trips too rapidly on Long Time Memory
function long delay
Disable Long Time Memory Refer to Section 4
Trip unit settings are not correct Change settings, Long Time Delay setting is based on 6 × I
r
Cause of Trip LEDs flashing and breaker is closed Trip unit was not reset from previous
event or test
Depress Reset pushbutton to clear LED flashing
Battery voltage too low to reset latch
chip and LEDs
Replace battery See Section 6
A Cause of Trip LED keeps retriggering in the
application (Digitrip 520M and 520MC)
Digitrip memory buffer not
completely reset
Need to reset Digitrip unit when Status LED is operational. Possibly do
this by temporarily (or permanently) adding auxiliary power and then
depress Reset pushbutton to fully clear trip buffer
See also Note in
Section 5
LCD Display is not energized Light load Check breaker ordering information Refer to Section 1
No auxiliary power unit Check voltage input terminals—A14, A15 Refer to Section 1
Circuit breaker containing Digitrip 520MC* does
not communicate with PowerNet or BIM.
*Only Digitrip 520MC styles have
communication features.
Wrong address Check address See Section 4
No power Check for auxiliary power—A14, A15
See Figure 1 and
refer to Section 1
Check Status LED and Transmit LED
Hardware problem Check communications wiring—B1, B2 See Appendix C
Missing termination resistor
See Figure 38
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