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Magnum Digitrip 520/520M/520MC

The Magnum Digitrip line of trip units consists of the 520, 520M, and 520MC for UL standards and models 520i, 520Mi, and 520MCi for IEC standards. Only models 520MC and 520MCi provide communications. Appendix B in the 520 series trip unit instructional leaflet includes a troubleshooting guide.

Protection settings options:

  • 520:
    • LI - Long delay, Instantaneous
    • LSI - Long delay, Short delay, Instantaneous
    • LSIG - Long delay, Short delay, Instantaneous, Ground Fault Trip
    • Instantaneous can be disabled for LSI and LSIG
  • 520M/520MC
    • LSI - Long delay, Short delay, Instantaneous
    • LSIG - Long delay, Short delay, Instantaneous, Ground Fault Trip
    • LSIA - Long delay, Short delay, Instantaneous, Ground Fault Alarm
    • Instantaneous can be disabled

External control power is not required to operate the basic overcurrent protection functions; the trip unit operates through current sensors mounted in the breaker. When the breaker trips, an LED on the trip unit will indicate the cause of trip.


  • 520:
    • Protection only.
  • 520M:
    • Current metering.
  • 520MC (520M features plus...):

The Ground Alarm/Power Supply Module:

  • Control power is connected to A14-A15.
    • This is designated as ATR_VOLT and ATR_V_COM on the wiring diagram. ATR = Automatic Trip Relay. For DC voltage, A14 (ATR_VOLT) is the positive, and A15 (ATR_V_COM) is the negative.
  • Four voltage ratings: 120 Vac, 230 Vac, 24–48 Vdc, and 125 Vdc.
    • +/-10% except for 125 Vdc which has an operating range of 100-140 Vdc.
  • 10VA power consumption.
  • Required on the 520M LSIA and all 520MC trip units. Optional for 520M LSI and LSIG.
  • With the ground alarm/power supply module the display will be functional even when the breaker has no load.
    • Without a power supply module (or applied control power), display will activate once the load current reaches approximately 30% single-phase or 10% three-phase of the In rating.
  • Without auxiliary power, there are no communications (520MC only), and the relay contacts will not be operational.
  • The green status LED blinks approximately once per second to indicate normal operations when the trip unit is powered from either load current or the power supply module.

Time/current curves are available on the Magnum website.

Factory default settings

Test kits

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