Burglar alarm for loss of phase and zero line drop of low-voltage circuit

Disclosed is an anti-theft alarm for loss of phase and zero line drop of low voltage line, relating to an alarm which alarms when the low voltage line has faults of loss of phase, zero line drop and wire steal and shear. The anti-theft alarm comprises a three-phase electric wire which provides three-phase electrical signals for an integrated block IC1 after voltage transformation and rectification. When the three-phase power supply is normal, an indicator light lights, and an alarming horn does not sounds to alarm; when either one or two phase is power off, the indicator light does not light, and the alarming horn sounds to alarm. The earth wire of the alarm is communicated with the common earth wire of the circuit; a zero line provides detection signals for the integrated block IC2 after rectification. At normal time, the horn does not alarm, but when zero line drop happens, the horn alarms. When either of the three phase power supply is power off, the anti-theft alarm alarms; the anti-theft alarm alarms when zero line drop happens, which can decrease the damage to the electric equipment caused by zero line drop or no-well contacted zero line; the anti-theft alarm uses luminous tubes with different colors and different alarm sounds to alarm separately, which is clear and visible. The utility model has reliable operation circuit, and can alarm when the phenomena of loss of phase, zero line drop and wiring stolen happen, and it can also be expanded to a remote control circuit with various forms.