User manual 09/2009 - Schneider Electric

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User manual 09/2009 - Schneider Electric

Operating AssistanceOperation of Pre-Alarm and Alarm LEDs (Electrical Distribution Protection)The pre-alarm (orange LED) and alarm (red LED) indications are tripped as soon as the value of one ofthe phase currents exceeds 90% and 105% respectively of the Ir pick-up setting:• Pre-alarmExceeding the pre-alarm threshold at 90% of Ir has no effect on activation of the long time protection.• AlarmCrossing the alarm threshold at 105% of Ir indicates that the long time protection (see Long TimeProtection, page 40) has been activated with a trip time delay that depends on:• The value of the current in the load• The setting of the time delay trNOTE: If the pre-alarm and alarm LEDs keep lighting up, it is advisable to carry out load shedding in orderto avoid tripping due to a circuit breaker overload.The figure below illustrates the information supplied by the LEDs:1 Current in the load (most heavily loaded phase)2 Thermal image calculated by the trip unitOperation of Alarm LEDs (Motor Protection)The alarm indication (red LED) is tripped as soon as the value of the motor thermal image exceeds 95%of the Ir pick-up setting.Crossing the threshold of 95% of Ir is a temperature alarm: long time protection is not activated.The figure below illustrates the information supplied by the LED:1 Current in the load2 Thermal image calculated by the trip unit132 LV434104 09/2009

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