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The advantage of neutral earthing is
Freedom from persistent arcing grounds
Over voltages due to lightning can be discharged to earth
Simplified design earth fault protection
All of the above
Freedom from persistent arcing grounds
Neutral earthing involves connecting the neutral point of a star-connected system (like a generator or transformer) to the earth, which stabilizes the system potential relative to the ground. This practice prevents unstable voltage conditions during faults and facilitates the safe operation of protective relaying equipment.
Neutral earthing involves connecting the neutral point of a star-connected system (like a generator or transformer) to the earth, which stabilizes the system potential relative to the ground. This practice prevents unstable voltage conditions during faults and facilitates the safe operation of protective relaying equipment.
VneutralтАЛтЙИ0 тАФ Ensures the neutral point remains at zero potential relative to earth
IfaultтАЛ=ZnтАЛVphaseтАЛтАЛ тАФ Fault current magnitude is determined by the earthing impedance ZnтАЛ
When a phase-to-ground fault occurs in an ungrounded system, the capacitive current to earth can cause intermittent arcing (arcing grounds) which generates severe voltage surges. By earthing the neutral, the fault current flows through a defined metallic or impedance path, allowing earth fault relays to detect the current imbalance and isolate the faulted section instantly, while simultaneously limiting the neutral potential rise.
Eliminates arcing grounds by providing a fixed reference potential.
Provides a low-impedance return path for earth fault currents.
Enables the use of sensitive and reliable earth-fault relay protection.
Reduces overvoltages caused by lightning or switching surges.
Improved safety for equipment and personnel
Clearer identification and isolation of faulted phases
Minimized voltage stresses on insulation
Stable phase-to-ground voltage levels
Requires additional protective equipment
Increased fault current magnitudes compared to isolated neutral systems
Power distribution transformers
Industrial motor protection systems
High-voltage transmission networks
Option A is correct because the neutral earth prevents the buildup of dangerous charges due to phase-to-ground capacitance.
Option B is correct because lightning surges can be dissipated to ground via the neutral connection rather than stressing line insulation.
Option C is correct because zero-sequence current detection becomes much simpler with a grounded neutral.
D is correct тАФ Neutral earthing provides a stable reference, facilitates fault detection, and protects insulation from surge-induced overvoltages.
Always remember that solid earthing leads to high fault currents, whereas resistance or reactance earthing is used to limit the magnitude of these currents during a fault.