LABORATORY INVESTIGATION OF IMPULSE CHARACTERISTICS OF DIFFERENT TYPE SOIL UNDER SEASONAL VARIATION FOR EFFECTIVE GROUNDING SYSTEM
Understanding the impulse characteristics of the soil where ground will be planted under seasonal variation is a key factor in the determination of the lightning performance of transmission lines and the safety voltages near high voltage towers. The earthing impedance is usually measured by either...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/46421 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Understanding the impulse characteristics of the soil where ground will be planted under seasonal
variation is a key factor in the determination of the lightning performance of transmission lines and
the safety voltages near high voltage towers. The earthing impedance is usually measured by either
switching DC to the earth rod or injecting low currents with frequencies close to the power
frequency. This resistance helps to estimate the behavior of the grounding system under low
frequencies. However, under lightning and impulsive transient conditions, the grounding system
exhibits different behavior. Many factors significantly affect the performance of the grounding
system, such as the resistivity and permittivity of the soil, the shape of earthing electrode, the
current magnitude and rise time of the impulse current. These aspects cause many challenges in
designing an effective grounding system to meet the safety operation requirements. This thesis
investigates both AC and impulse characteristics of the soil with different water content when the
soil is subjected to AC variable frequency and impulses voltage respectively. The prepared soil
with different water content was mixed LRM. The results obtain before adding the LRM compared
with the developed models available in literature exhibited close agreements with them. However,
the impulse experiment tests show that, the impulse characteristics of the soil before and after
adding LRM were totally different. The impulse impedance decreases with soil water content,
additional of LRM, and amplitude of impulse current. Effect of moisture contents on the resistivity
of soil and the electrical soil parameters depend on the frequency due to the soil permittivity. Both
AC and impulse characteristics of the soil under season variation are the paramount parameters to
be considered in designing the effective ground system to improve the withstand and performance
of power system. |
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