Earthing Or Grounding(Electrical Engineering ) Questions and answers for exam Preparation

Question 1. When the 3-phase system is not grounded and if Single Line to Ground fault occurs, the voltage of the other two healthy phases will

Increases
Decreases
Remains unaffected
none of the above

Explanation:-

Answer: Option A. -> Increases

Question 2. Ground resistance should be designed such that

grounding resistance should be as low as possible
grounding resistance should be as high as possible
grounding resistance should be always zero
none of the above

Explanation:-

Answer: Option A. -> grounding resistance should be as low as possible

Question 3. Moisture content in the soil _______ the earth soil resistance

increase
decrease
does not affect
none of the above

Explanation:-

Answer: Option B. -> decrease

Question 4. Generally grounding is provided for

only for the safety of the equipment
only for the safety of the operating personnel
both (A) and (B)
none of the above

Explanation:-

Answer: Option C. -> both (A) and (B)

Question 5. For an EHV equipment for maintenance first it should be isolated and connected to ground because

to provide low impedance
to discharge the charging capacitance to ground
protection for operating personnel
both (B) and (C)

Explanation:-

Answer: Option D. -> both (B) and (C)

Question 6. The size of the earth or ground wire is based on the

maximum fault current carrying through the ground wire
rated current carrying capacity of the service line
depends on the soil resistance
both (A) and (C)

Explanation:-

Answer: Option D. -> both (A) and (C)

Question 7. The objective of earthing or grounding is

to provide as low resistance possible to the ground
to provide as high resistance possible to the ground
to provide flow of positive, negative and zero sequence currents
none of the above

Explanation:-

Answer: Option A. -> to provide as low resistance possible to the ground

Question 8. Average resistance of human body is

500 ohms
1000 ohms
1500 ohms
2000 ohms

Explanation:-

Answer: Option B. -> 1000 ohms

Question 9. Factors on which soil resistance depends

depth of the electrode
moisture
Nacl
all the above

Explanation:-

Answer: Option D. -> all the above

Question 10. When earth fault occurs

voltage potential at the earth mat increases due to grounding
voltage potential at the earth mat decreases due to grounding
voltage potential at the earth mat remains zero irrespective of fault
none of the above

Explanation:-

Answer: Option A. -> voltage potential at the earth mat increases due to grounding