The invention relates to the technical field of
welding power supplies, in particular to a three-phase
electricity over-
voltage, under-
voltage and default phase alarm circuit based on peak
voltage detection. The alarm circuit comprises a first
diode, an over-voltage detection circuit and a rapid-charge and slow-
discharge logic comparison circuit, the first
diode is connected with any phase of three-phase
electricity, one path of an input end of the over-voltage detection circuit is connected with the first
diode, the other path of the input end is connected to any phase of the other two phasesof the three-phase
electricity, an output end of the over-voltage detection circuit is connected when the voltage exceeds a threshold value, the rapid-charge and slow-
discharge logic comparison circuit is connected with an output end of the over-voltage detection circuit and comprises a rapid-charge and slow-
discharge circuit and a first logic comparison circuit, an
energy storage element of therapid-charge and slow-discharge circuit is charged to generate voltage higher than reference voltage when the output end of the over-voltage detection circuit is connected, the
energy storage elementof the rapid-charge and slow-discharge circuit discharges and keeps voltage higher than the reference voltage when the output end of the over-voltage detection circuit is disconnected, an output end of the rapid-charge and slow-discharge circuit is connected with a
comparator and compared with the reference voltage, and an output end of the
comparator is connected with an
alarm device.