Patent ID: 7649725

Claim:
A power limiting circuit, comprising: a relay for controlling the on/off of a load; a silicon controlled rectifier for controlling the switching of the relay between normally open contact and normally closed contact; a sampling circuit for sampling an output loop current; a control chip for comparing the voltage value of the sampling circuit with a standard voltage value and triggering the conduction of the silicon controlled rectifier; a low-voltage direct current power supply for supplying the standard voltage to the control chip; wherein the control chip is provided with a standard voltage end and a sampling end, the sampling end is divided into two parts, one part is connected in series to a resistor (R 2 ) and then connected to negative end of the low-voltage direct current power, the other part is connected to the sampling circuit that consists of two parallel connected resistors (R 9 and R 10 ) one end of the sampling circuit is connected in series to resistors (R 11 and R 8 ) in sequence and then connected to sampling end of the control chip, the other end of the sampling circuit is connected to negative end of the low-voltage direct current power supply.