Design of a Low Cost Microcontroller Based High Impedance Fault Detector

A conductor sags or broken and touch the ground causing a high impedance fault. The fault current is low and typically closes to the load current therefore overcurrent relay cannot detect the fault. If the fault stays on it may harm people passing by. This paper propose low cost microcontroller based high impedance fault detector. The algorithm applies wavelet transforms to detect high impedance faults. The high impedance fault detection was then tested by using the fault currents from simulations and the current waveforms captured by a fault recorder from the experiment on a 24 kV distribution feeder. The results from the simulations and the real situation will be shown in the paper.