The advantage of neutral earthing is

A. Freedom from persistent arcing grounds

B. Over voltages due to lightning can be discharged to earth

C. Simplified design earth fault protection

D. All of the above

Answer: D. All of the above

Explanation: 

Earthing:

• The process of connecting the metallic frame (i.e. non-current carrying part) of electrical equipment or some electrical part of the system (e.g. neutral point in a star-connected system, one conductor of the secondary of a transformer etc.) to earth (i.e. soil) is called grounding or earthing.
• Earthing is generally done in the transmission line at the supply end to safeguard the whole system from flowing high fault currents whenever any fault occurs in the system.

Advantages of neutral grounding:

• Voltages of the healthy phases do not exceed line to ground voltages i.e. they remain nearly constant.
• The high voltages due to arcing grounds are eliminated.
• The protective relays can be used to provide protection against earth faults.
• In case an earth fault occurs on any line, the protective relay will operate to isolate the faulty line.
• The over-voltages due to lightning are discharged to earth.
• It provides greater safety to personnel and equipment.
• It provides improved service reliability.
• Operating and maintenance expenditures are reduced.
• The simplified design of earth fault protection.
• Over-voltages due to lightning can be discharged to the earth.
• Freedom from persistent arcing grounds.