Simulation and Measurement of the Magnetic Field Signature of a Vacuum Circuit Breaker and the Identification of Arcing

Magnetic field emission of circuit breakers during load switching contains valuable information. Our previous work has shown the application of the magnetic field signature during load-switching events to measure the arc duration and to detect potential malicious intrusion of the substation. To apply the approach to a wide variety of circuit breakers, a simulation model is required due to the complexity of circuit breaker experiments. This paper establishes a model to simulate the circuit breaker magnetic signature generated during load-switching events and a suitable approach to process the signal from the measurement system. Four models have been built to simulate the influence of each step on the B-field waveform. The physical connection between the magnetic signatures and the circuit breaker load switching is explained based on the results. The model is verified by comparing simulated results with the magnetic field measurements from a real vacuum circuit breaker when it cuts off an alternating current of up to 2.5 kA (peak). The difference between the simulated and measured magnetic field and the possible reasons that cause the discrepancy are discussed. The model serves as a start point for accurately simulating the magnetic signatures. Several optimizing approaches are proposed for future study to improve the simulation model and enable the simulation of circuit breakers with different structures and arc-extinguishing technologies.