The present application provides a
system and method for online monitoring of the
contact resistance of a break of a
circuit breaker. The
system includes a main circuit formed by connecting a
circuit breaker, a shunt, a load, and a power supply; a
voltage transducer is connected in parallel at the break of the
circuit breaker, the
voltage transducer includes an auxiliary protection circuit connected in parallel at the break of the circuit breaker, the auxiliary protection circuit includes a first
branch and a second
branch each composed of a switch and a first
resistor, the switches are connected to the break of the circuit breaker, ends of the two first resistors away from the break are each connected in parallel with a second
resistor and a protection element, and end ports of the first
branch and the second branch are used to collect a
voltage value at the break of the circuit breaker; a
current transformer is connected in parallel with two ends of the shunt, and the
current transducer is used to monitor a current value at the break of the circuit breaker; and the
contact resistance of the break is obtained by calculation on the basis of the voltage value and the current value being monitored. The present application can achieve online monitoring of the
contact resistance of a break of a circuit breaker, and prevent the voltage
transducer from burning due to over-voltage caused by breaking at the break.