Flux Linkage Detection Based Ground Fault Identification and System Diagnosis in High-Resistance Grounding Systems

Abstract

High-resistance grounding (HRG) is preferred in many industrial applications where the operation continuity is critical under ground fault conditions, such as pulp, paper, oil refining, chemical, glass, and metal industries. This is due to: 1) continuity of service; 2) minimized productivity impact with the scheduled system downtime; and 3) improved safety concerns—elimination of phase to ground arc flash hazards, suppression of transient line to ground overvoltages, and minimization of the equipment damage at the point of ground fault. However, there are also some drawbacks in accurately detecting and locating a ground fault in adjustable speed drive (ASD) systems: 1) the HRG fault current (1–10 A) cannot reliably trip the overcurrent protection function in drives; 2) the existing methods are based on the line voltage/frequency (50/60 Hz), making it hard to detect and locate low-voltage/low-frequency ground faults; and 3) with the existing methods, the possible fault locations will be manually checked one by one using an Ammeter by a trained technician. This paper will present a flux linkage detection based HRG fault identification method for ASD systems. The proposed method can solve: 1) reliable HRG fault detection with wide motor speed range; 2) the HRG fault can be easily identified in multiple systems; and 3) the identification process is performed by the proposed system diagnosis method, no trained technician is required during the identification process.