Characteristic study of vertical configuration grounding system with two layer modified using type of different soil for variation of diameter and frequency injection

Abstract

Grounding impedance are affected by current injection, grounding configuration, and factors that affecting soil. Current injection at low frequency, makes the properties of grounding impedance is resistive but at high frequency, the properties of capacitive and inductive should be considered. Limited environmental condition determine that what grounding configuration will be used. The factor which affect soil such as low moisture will make high grounding impedance value. This problem can be solved with soil treatment or modify grounding system. In this research was made modification grounding system of vertical configuration. This modification was made with filling soil inside grounding rod which was formed cylinder (cylinder rod). This cylinder was planted in ITB campus. ITB's soil has composition: 16.85% clay, 66.18% silt, 15.48% sand, and 1.49% gravel. Soil that using for filling cylinders was taken from Nanjung, Bandung with composition: 34.98% clay, 49.55% silt, 15.35% sand, and 0.16% gravel. For determining the effect of diameter from this grounding system, so that is made 3 cylinder rods variation with fixed length (l = 50 cm) and variation of diameters are 20 cm, 30 cm, and 40 cm. The grounding rod was injected frequency range 1 Hz to 15 MHz with low current. The result of research is variation of diameter affects grounding impedance value become small at high frequency (1 MHz – 14.3 MHz). At frequency injection range 1 MHz – 3 MHz and 9 MHz – 14.3 MHz, the smallest of grounding impedance value on cylinder rod with diameter 20 cm. At frequency range 4 MHz – 8 MHz, the smallest of grounding impedance value is cylinder rod with diameter 40 cm. The properties of resistive, inductive, and capacitive depend on frequency injection.