An alternative approach for touch and step voltages measurement in high-voltage substations

This paper presents the study of a measurement technique for touch and step voltages. In essence, we elaborate an approach which is very similar to the measurement of the grounding system impedance. In addition, the main focus is on the measurements at energized substation where different types of coupling between the test leads, grounding grids, sheats of underground cables and overhead ground wires affect the precise measurement. In order to avoid the measurement difficulties, we use low magnitude variable frequency AC test current (so called Frequency Shift Method – FSM). We compare FSM measurement results with the corresponding results obtained by well-known Test Current Reversal Method. The field tests were conducted in two quite different substations. Experimental results demonstrate the validity and usability of this approach.