Research on Elevator Operation Harmonic Current Characteristics Analysis and Electrical Fire Detection Technology

The elevator will generate high-frequency harmonic current during operation, and the leakage current generated by the high-frequency harmonic current to ground will cause interference to the residual current type electrical fire monitoring detector due to the existence of parasitic capacitance in the distribution line. This paper analyzes the high-frequency interference signals generated during the operation of elevators and studies the residual current analysis method based on digital filtering technology. Firstly, the causes of false alarms generated by residual current type electrical fire monitoring detectors are analyzed according to the residual current interference signals generated during elevator start-up. Then, the frequency characteristics of the disturbance signal of the elevator in different operating states are proposed by analyzing the spectrum of the disturbance signal during the stationary, ascending, and descending processes of the elevator. Finally, the method of using a fast Fourier transform to analyze the residual current in elevator distribution lines is presented. The experimental results show that the frequency of the residual current interference signal generated when the elevator is running is mainly distributed above 3000 Hz, the energy of the interference signal at 3700 Hz is the largest when the elevator is stationary, and the energy of the interference signal at 4500 Hz is the largest when the elevator is ascending or descending. The amplitude of the signal can be used as a criterion for whether the distribution line generates leakage.