Security Monitoring of Railway Power Cable Joints Based on AD7606 AC Synchronization Sampling

Abstract

To avoid the frequent accident of burning loss of railway 10kV power cable joints, an online monitoring device is developed based on tanδ, the tangential value of loss angle of the cable’s main insulation, and other state variables, to carry out real-time monitoring and safety evaluation of the cable’s running state, so as to timely alarm and predict hidden accident danger for abnormal cable joints. The measurement of tanδ adopts a frequency correction method based on AD7606 AC synchronous sampling and FFT phase difference frequency correction, which can avoid the spectrum leakage effect of asynchronous sampling and the phase-locked loop synchronization circuit with complicated cost. This paper regards the current source of grounding wire of railway cable when no electric locomotive passes through the railway electrical section as leakage current of the main insulation of cable. Tanδ is monitored by collecting and processing the voltage of cable bus-bar potential transformer and the current of cable grounded wire.