Low Voltage Fault Research Articles

A Complete Field Analysis of Substation Ground Grid By Applying Continuous Low Voltage Fault

A field investigation of a ground grid using continuous 60Hz power source was carried out in a 115/12kV distribution substation. Field measurements included the grid potential rise (GPR), surface voltage gradients and distribution of the fault current. Four different fault locations were investigated to determine the worst fault and its location. By scaling up the measured data, safety-related grounding parameters corresponding to a full scale fault, are determined. Measured data is compared with computer calculated data. The field test presented in this paper can be a valuable tool for utilities to analyze ground grids for assessing safety and for verifying the design method by comparing the design parameters with the measured data.

Clearing Low-Voltage Ground Faults with Solid-State Trips

The danger of undetected ground faults on low-voltage systems is reviewed, and the destruction that arcing faults can cause is explained. The methods of clearing ground faults are discussed, and an economical method of ground-fault tripping is presented. This uses solid-state components to provide a static trip device for low-voltage power circuit breakers which initiates tripping for low magnitude ground faults as well as phase faults and overloads. Coordination curves of a typical system showing selective phase and ground-fault tripping are included.