Mechanical Fault Detection System Of Low Voltage Circuit Breaker Based On Multiple Feedback Self-mixing Interference

Low voltage circuit breakers are widely used in low voltage distribution networks.They can play a role of protection and control.Their normal work is the key to the safe operation of distribution networks.Therefore,timely detection of low voltage circuit breaker fault is particularly important.Mechanical fault accounts for more than half of the fault of low voltage circuit breaker.Vibration wave will be collected during the closing process of low voltage circuit breaker,and the effective vibration characteristics of the circuit breaker can be extracted as the basis for fault detection.In this paper,the multiple feedback self mixing interference technique is used to collect the vibration signals of low voltage circuit breaker,and the signal is analyzed with the wavelet packet energy spectrum method,and the effective eigenvalues are obtained,and then the fault is detected.The fault detection methods for low voltage circuit breakers are studied and analyzed.The disadvantages of contact sensing method for vibration signal measurement,the advantages of self mixing interferometry and the application of self mixing interferometry in the field of vibration measurement are illustrated.The theoretical model of multiple feedback self mixing interference is studied and derived,and the measurement accuracy is analyzed.Based on the simulation of theoretical values,the waveform of multiple feedback self mixing interference signals under different optical feedback coefficients is obtained,and the effect of the optical feedback factor on the multiple feedback self mixing interference signals is analyzed.Simulation and comparison of multiple feedback self mixing interference waveforms are carried out for different feedback levels.Aiming at the problem that the accuracy of self mixing interference reconstruction can be further improved,a vibration reconstruction technique based on multiple feedback self mixing interference is proposed.The EOM is placed in the external cavity of the laser,and the light emitted by the laser is modulated sine phase.The multiple feedback self mixing interference signal after modulation is demodulated with the four quadrant integral demodulation algorithm,and the vibration wave is reconstructed according to the demodulated phase.In view of the mechanical fault signal detection of low voltage circuit breaker,a low voltage circuit breaker fault detection platform based on multiple feedback self mixing interference vibration reconstruction technology is designed and built.The vibration signals of low voltage circuit breakers in non-contact and high precision are reconstructed under normal and fault conditions,and the wavelet packet energy spectrum analysis method isobtained.The experimental results show that the low voltage circuit breaker has good feasibility in the low voltage circuit breaker fault detection,and provides preliminary research and help for the establishment of fault feature knowledge base and the development of fault detection.