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The proximity effect is very significant to investigate transient peak voltages and EMC related problems of a conductor system. In this paper, effect of energized single conductor in close proximity of an Al plate when an Al plate is used as return path is investigated to find out proximity effect. The analysis involves simulation by the Finite Time Domain Method (FDTD) in comparison with field measurements. It is observed that the current distribution is uneven in pipe conductor due to the proximity effect of varying heights from ground.

The series impedance and shunt admittance are conductor or cable parameters needed in simulation models for conductor system. These quantities describe the electromagnetic behavior of the system. The series impedance needed in simulation of conductor or cable transients is commonly calculated using formulae that neglect the presence of proximity effects using EMTP Cable Constants routine [

The proximity effect influences the distribution of current which flows via conductor to the ground and thus should be taken into account when calculating the overall impedance of a conductor system. This influence, or proximity effect, always appears when the part of conductor system is too close together. It is manifested in an increase of the total impedance, compared with the value obtained when those parts are sufficiently distant. The numerical method FDTD (Finite Differential Time Domain) used in the paper demonstrates that the proximity effect has appreciable significance for conditions in proximity which are regarded as standard and normal in power system installations. The paper presents an experiment measurements case of single conductor for obtaining influence of the surrounding ground in close proximity but due to instrumental limitations and human errors they are as accurate as expected.

A step-like voltage is applied to the center point of the Al pipe. All the voltages are measured by an oscilloscope (Tektronix DPO 4104, 1 GHz) and a voltage probe 2500 V pk Tektronix made. Six resistors of 100 Ω connected 60˚ apart at receiving end of an Al pipe and terminated at center point. The distribution of current which flows from the conductor to ground are measured to observe effect of close proximity for varying height from h = 5.5 cm to h = 50 cm i.e. 2r, 4r and 10r to investigate proximity effect.

injected currents for all heights.

A numerical electromagnetic analysis is becoming a very powerful approach to solve a transient which cannot be handled by circuit-theory based approach such as the EMTP. It is based on Maxwell’s equations expressed in a discrete representation so that various incident, reflected and scattered fields can be calculated by digital computers. These discretized Maxwell equations form the foundation of the Finite Difference Time Domain (FDTD) method to the solution of electromagnetic propagation problems [

^{–8} corresponds to experimental value. The front end of the cylinder is energized at center point by a pulse generator. At the rear end of the pipe six resistors of 100 Ω is arranged as illustrated in

z-direction cells are gradually increased with increasing distance from Aluminum plate (5.5 cm, 10 cm, 20 cm, and 50 cm). The grounding point is represented by conducting disc at the receiving end to enclose the cylinder. An equivalent radius of conducting cylinder is represented in corresponds to experiment that is 5 cm. This conductor system is represented with cell size Δs = 5 mm.

The FDTD simulation model in VSTL view is as shown in

investigation. Therefore, mainly short-circuited receiving condition is studied and discussed.

The FDTD simulations are carried out with appropriate cell size to keep real height equals to virtual height in terms of no of cells from ground as given in

V/m (1)

Faraday’s law of induction states that E-field is equal to the rate of change of the voltage with respect to distance. The differential amount of EMF at any point along the circuit is equal to the E field at that location. Since measurement voltages at points 60˚ apart is known, it is possible to calculate electrical field from measured voltages.

Similarily, using Bio Servart law magnetic field at perticar point can be calculated by below formulae.

A/m(2)