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Neutral earthing has the advantage of
Elimination of arcing grounds
Low maintenance and operating cost over isolated neutral system
Simplified design of earth fault protection
All of above
All of above
Neutral earthing involves connecting the neutral point of a star-connected system (like a generator or transformer) to the earth, either directly or through an impedance. This practice provides a return path for fault currents, ensures stable potential for phases, and facilitates the detection of ground faults.
Neutral earthing involves connecting the neutral point of a star-connected system (like a generator or transformer) to the earth, either directly or through an impedance. This practice provides a return path for fault currents, ensures stable potential for phases, and facilitates the detection of ground faults.
VphтАЛ=3тАЛVLтАЛтАЛ тАФ Voltage reference maintained in a balanced earthed system
IgтАЛ=ZnтАЛVphтАЛтАЛ тАФ Ground fault current magnitude controlled by neutral impedance ZnтАЛ
In an isolated neutral system, a single line-to-ground fault creates a capacitive charging current through the system capacitances to ground, often leading to intermittent arcing grounds and high overvoltages. Neutral earthing bypasses these capacitances by providing a defined zero-potential reference and a controlled path for zero-sequence current, thereby suppressing transient voltage oscillations.
Neutral earthing provides a stable reference for phase-to-neutral voltages.
It prevents the build-up of dangerously high transient voltages caused by intermittent arcing grounds.
It allows for the usage of sensitive earth fault relays, which reduces equipment damage during insulation failure.
Solid earthing is common in LV systems, while resistance or reactance earthing is used in MV/HV systems.
Elimination of arcing grounds
Improved safety for personnel and equipment
Simplified earth fault relay coordination
Reduction in overvoltage stress on insulation
Increased fault current levels for solid earthing
Possible interference with communication circuits
Requirement for additional equipment like grounding transformers or resistors
Transmission lines
Industrial distribution systems
Generator neutral points
Arcing grounds are unstable intermittent arcs caused by the charging currents of the healthy phases in an isolated system.
By earthing the neutral, the voltage of healthy phases remains locked to the line-to-neutral voltage during a single line-to-ground fault.
D is correct тАФ Neutral earthing provides a low-impedance path for ground fault currents, stabilizing system voltage and allowing for effective protection schemes.
Always remember: If the question asks for the primary reason for neutral earthing, 'Elimination of arcing grounds' is the historical driver, whereas 'Simplified protection' is the operational necessity.