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Advantage of neutral earthing is
Safety to personnel
Reduction of earth fault current
Elimination of arcing ground
None of above
Elimination of arcing ground
Neutral earthing is the practice of connecting the neutral point of a star-connected system (such as a generator or transformer winding) to the earth, either directly or through an impedance. Its primary purpose is to eliminate arcing grounds, which are intermittent or unstable arcing faults that can cause dangerous high-frequency voltage oscillations in an ungrounded system.
Neutral earthing is the practice of connecting the neutral point of a star-connected system (such as a generator or transformer winding) to the earth, either directly or through an impedance. Its primary purpose is to eliminate arcing grounds, which are intermittent or unstable arcing faults that can cause dangerous high-frequency voltage oscillations in an ungrounded system.
VarcтАЛтЙИ3VphтАЛ тАФ Voltage magnitude during arcing grounds in ungrounded systems
IfтАЛ=ZnтАЛVphтАЛтАЛ тАФ Fault current determined by neutral grounding impedance ZnтАЛ
In an ungrounded system, a single line-to-ground fault creates a capacitive circuit involving the line-to-earth capacitance of the healthy phases. This often leads to an 'arcing ground' condition where the capacitance discharges through the arc path, causing transient overvoltages that can reach 3 to 4 times the line voltage. Neutral grounding provides a low-impedance return path for fault current, forcing the potential of the faulted phase to ground and quenching the arc, thereby stabilizing system voltage.
Eliminates the 'arcing ground' phenomenon by providing a discharge path.
Limits the voltage of healthy phases to the line-to-neutral value.
Simplifies the use of earth-fault protection relays.
Prevents arcing faults from escalating into phase-to-phase faults.
Elimination of arcing grounds
Effective operation of protective gear
Simplified fault localization
Introduction of earth fault currents
Potential interference with nearby communication lines
High voltage transmission systems
Industrial distribution networks
Generators and transformer secondaries
Arcing grounds occur when the system capacitance CeтАЛ resonates with the inductance of the line during a fault, causing voltage escalation.
Option A is incorrect because safety to personnel is primarily provided by equipment (frame) earthing, not neutral earthing.
Option B is incorrect because neutral earthing typically increases fault current compared to an ungrounded system.
C is correct тАФ Neutral earthing provides a low-impedance path to drain capacitive currents, which effectively eliminates the voltage spikes and insulation stress caused by arcing grounds.
Always distinguish between 'System Earthing' (neutral point to earth) for safety and arc control, and 'Equipment Earthing' (non-current carrying metal parts to earth) for human safety.