GROUNDING METHODS AND ITS ADVANTAGES

WHY GROUNDING IS IMPORTANT

Grounding is an important factor in an electrical system proper grounding reduce overvoltages, improves uptime, and isolates faults and thus the grounding system provides protection for the electrical system

GROUNDED SYSTEM TYPES

SOLIDLY GROUNDED

This type of grounding system connects the system neutral directly to the earth ground and this will ensure that the neutral voltage is equal to the ground and thus each individual phase to neutral voltage is fixed with a reference to the ground by the grounded neutral by doing this properly we can make sure that phase to ground overvoltages will not occur, the solidly grounded system must be done properly so it bonds the neutral ground at one point, if the grounding is not properly done it would create ground faults so during this fault a large amount of current will flow and it is needed to remove the source and it would affect the system reliability and load availability

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RESONANT GROUNDED

This is grounded by using a variable inductance called Petersen coil and it is in series with the effective line to the ground capacitance of each phase conductor and it is tuned to produce an impedance based on the series LC circuit and the Peterson coil needs to be adjusted according to what is connected at that time

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LOW RESISTANCE GROUNDING

This type of grounding is used to reduce the damage which is caused by the high currents during the ground faults this system is used in medium voltage and low voltage systems, so the current is reduced but the magnitude of the fault current is still large that the source must be disconnected

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HIGH RESISTANCE GROUNDED (HRG)

It is similar to the low grounding resistor except that the neutral grounding resistor with a higher value is chosen for this type of grounding and it will reduce the ground fault current to lower values and there won’t be any need to trip this type of grounding system are also used for detecting the ground faults and it will repair the faults quickly and it would increase the reliability

HYBRID HIGH RESISTANCE GROUNDED

These are used for special cases to protect generators from internal ground faults it operates as a low resistance grounded system with a bypass device closed under normal condition, the bypass device will open if the fault is detected and the ground current is forced through and it will reduce the current

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ADVANTAGES OF GROUNDING THE ELECTRICAL SYSTEM

  • Magnitude of transient overvoltage is reduced
  • Ground fault location can be easily detected
  • Reduced maintenance time and expense
  • Personnel safety is improved
  • Lightning protection
  • Frequency of faults is reduced