User manual 09/2009 - Schneider Electric

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User manual 09/2009 - Schneider Electric

Operating AssistanceLocal LED IndicationLocal Indicator LEDThe number of LEDs and their meaning depend on the type of Micrologic trip unit.Type of MicrologicDescriptionDistribution • Ready LED (green): Blinks slowly when the electronic trip unit is ready to provideprotection.• Overload pre-alarm LED (orange): Shows a steady light when the load exceeds90% of the Ir setting.• Overload alarm LED (red): Shows a steady light when the load exceeds 105% ofthe Ir setting.Motor • Ready LED (green): Blinks slowly when the electronic trip unit is ready to provideprotection.• Overload temperature alarm LED (red): Shows a steady light when the motorthermal image exceeds 95% of the Ir setting.Operation of the Ready LEDThe Ready LED (green) blinks slowly when the electronic trip unit is ready to provide protection. Itindicates that the trip unit is operating correctly.NOTE: Activation of the Ready LED is guaranteed for a value equal to the sum of the circuit breakercurrent intensities for each phase and the neutral above a limit value.This limit value is indicated above the Ready LED, on the front face of the Micrologic trip unit.The table below uses 2 examples to illustrate the comparison of the phase and neutral currents with theactivation limit value of the Ready LED:Micrologic 5.2 Trip Unit, 40 A Rating, 3-PoleMicrologic 5.3 Trip Unit, 400 A Rating, 4-PoleThe limit value is 15 A. The limit value is 50 A.This limit value can correspond, for example:• Either to the sum of the 5 A phase current intensities(3 balanced phases)• Or to 7.5 A in 2 phases (the current intensity in thethird phase is zero)• Or to 15 A in one phase if the circuit breaker (3-pole):• Is installed on a distribution with distributed neutral• Only has one loaded phase on a single-phase loadThe current intensity in the other 2 phases is zero.This limit value corresponds, for example:• Either to the sum of the three 15 A phase currentintensities and a 5 A neutral current intensity• Or to 25 A in 2 phases (the current intensity in the thirdphase and in the neutral is zero)• Or to 25 A in one phase and in the neutral (the currentintensity in the other 2 phases is zero)LV434104 09/2009 131

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