Effect of Ground Electrodes on the Susceptibility to Damage of Customer Premises Equipment (CPE) under Impulse Conditions

Usman Muhammad,Nurul Nadia Ahmad,Normiza Mohamad Nor,Annuar Mohd Ramli

doi:10.3390/en15031247

Abstract

One of the requirements for the safe operation of customer premises equipment (CPE) is an adequate grounding system as a means to divert high fault currents to the ground. In this work we report on the results of an experimental study of the impulse characteristics at a charging voltage of 30 kV on the surge protective device connected to 16 earth electrodes and installed at two sites, giving various ground resistance at low voltages, RDC values. All of these grounding electrodes were installed and tested under the same charging voltage to determine the effectiveness of ground electrodes toward the damage of a modem at the premises. We observed that modems did not experience damage when the ground electrode of the distribution pole (DP) had an RDC below 30 Ω in general and below 46 Ω when ground electrodes installed in low resistivity soil were used. The impulse polarity did not affect the damage susceptibility of the CPE.

Highlights

A good grounding system is necessary to provide the path for a high magnitude of current to be discharged into the ground and to reduce the voltage rise in the vicinity of the grounding system subjected to high impulse
This paper focuses on the effect of the ground electrodes at the distribution pole (DP), where the effective RDC values from this study can be applied as a basis of grounding systems for modems
This paper contributes to the proposed ground resistance value that is suitable to be used at the DP, which will not cause damage to the customer premises equipment (CPE)

Summary

Introduction

A good grounding system is necessary to provide the path for a high magnitude of current to be discharged into the ground and to reduce the voltage rise in the vicinity of the grounding system subjected to high impulse. As generally defined in many standards [1,2], a low ground resistance value RDC is required so that a high current can be effectively discharged to the ground, and the voltage rise can be reduced. Ground electrodes cannot be varied since the testing was carried out at the designated site of a telecommunication station where the areas were limited only to the specific site For this reason, this paper attempted to determine the effective RDC value that was suitable and considered acceptable to be used along with the modem. Impulse tests were carried out on various ground electrodes that were installed at two sites and connected to the modem, where the ground resistance value RDC that will not cause damage to the modem was determined. This paper contributes to the proposed ground resistance value that is suitable to be used at the DP, which will not cause damage to the CPE

Impulse Test Equipment

Testing Sites

Ground Electrodes

Measurements from Voltage Divider 1 and Current Transformer 1

Conclusions