Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Resistance earthing is employed for voltage below
3 kV and 11 kV
11 kV and 33 kV
33 kV and 66 kV
66 kV and 132 kV
3 kV and 11 kV
Resistance earthing is specifically employed in electrical power systems for voltage levels below 3 kV and 11 kV to limit the fault current during a line-to-ground fault. This method provides a compromise between solid earthing and isolated neutral systems by inserting a resistor in the neutral-to-ground path.
Resistance earthing is specifically employed in electrical power systems for voltage levels below 3 kV and 11 kV to limit the fault current during a line-to-ground fault. This method provides a compromise between solid earthing and isolated neutral systems by inserting a resistor in the neutral-to-ground path.
IfтАЛ=RnтАЛVphтАЛтАЛ тАФ where IfтАЛ is the restricted earth fault current, VphтАЛ is the phase voltage, and RnтАЛ is the neutral earthing resistance
The resistor in the neutral path limits the earth fault current to a predetermined value, typically close to the full-load current of the transformer. This reduction in fault current helps in protecting generator windings and transformer coils from excessive mechanical and thermal stresses while still allowing enough current to trip sensitive relay protection.
Used to prevent transient overvoltages associated with arcing grounds.
Limits fault current to a safe range, reducing damage to equipment.
Most effective in medium-voltage distribution networks (3.3 kV, 6.6 kV, 11 kV).
Requires high-wattage resistors capable of handling fault energy.
Reduces damage at the point of fault.
Reduces interference with nearby communication lines.
Limits mechanical stresses on transformer windings.
Resistor is subject to high thermal stress during faults.
Requires complex protection schemes compared to solid grounding.
Industrial power systems at 3.3 kV and 6.6 kV levels.
Auxiliary systems in power stations (11 kV).
Solid earthing is typically used for low voltages (below 1 kV) and very high transmission voltages (above 132 kV).
Resistance earthing provides a middle ground for medium voltage levels to ensure safety and equipment longevity.
A is correct тАФ Resistance earthing is effectively used for voltage levels in the 3 kV and 11 kV range to control fault currents.
Always remember: Solid earthing is for LV and EHV, while Resistance/Reactance earthing is reserved for MV systems to balance fault severity.