A Simulation Model to Analyze Current Split Distribution of Multiple Temporary Protective Grounds (TPGs)

Abstract

The main purpose of Temporary Protective Grounds (TPGs) is to maximize personnel safety while working on any de-energized power equipment. ASTM F855 specified the required designs for individual TPG configurations. In recent times, installing more than one TPG for high fault current applications is a widely accepted practice. The use of multiple TPGs on a single phase conductor would limit current carrying capability of an individual TPG by splitting the high fault currents among the parallel TPGs. The current split between the parallel TPGs depends on the resistance of the individual TPGs and the spacing present between TPGs. However, performing multiple high fault current test configurations at a laboratory is extremely complex and expensive. A three TPG configuration was designed and tested at 80 KA as per ASTM F855 requirements and the current split measurements were taken on each individual TPG. A simulation model was designed to perform different multiple TPGs configurations and the model was verified by comparing with the laboratory test results. An example test case is discussed using the simulation model where if one of the parallel TPGs has high impedance values and the simulation results indicate that the change in resistance of the TPGs impact the current split distributions adversely.