For 1 kv to 33 KV The earthing Resistance Should be less
than 0.5 ohm.
For Domestic Purpose it should less than 2 ohm
Upto 1 Kv It should be in between 1 to 2 ohm
for EHV it should be less than 0.01 ohm
The Earthing Resistance of a household should not be
greater than 5-Ohm. This is in keeping with the Indian
Stadards, so also the international standards, viz, IEEE
(Institution of Electrical & Electronic Engineers) and IEC
(International Electrotechnical Commission) which stipulate
that no Earthing Resistance shall be greater than 5-Ohm.
The restriction is required to ensure the safety of the
occupants and the electrical appliances.
The Earthing Resistance of a Power Station should not be
greater than 0.5-Ohm because a Power Station is required to
carry high earth currents.
The Earthing Resistance of a Major Substation such as
a "Receiving Station" or a 400kV/220kV/110kV/66kV etc
Transmission or Stepping Up/Down Substations should not be
greater than 1-Ohm.
The Earthing Resistance of a Minor Substation such as an
11kV/230V Distribution Substation should not be greater
This clarifies my first answer.
industrial earthing resistence should be very betwwen .5
ohms to 5 ohms.
0.5 to 1 ohms- very good
1 ohms to 1.5 ohms- good
1.5 to 2.0 ohms-satishfactory
2.0 ohms to 5 ohms- not satisfactory.
note imp- This resistence consider of near induviusal
earth pit only.equipement earthing value should be very
betwwen 0.5 ohms to 12 ohms depending on size & distence of
earthing netwerk(GI PATTI OR COPPER PATTI OR WIRE)utilise.
ACTUALY IN EARTHING RESISTENCE OF INDUSTRIES OR RESIDENT OR
SUB STATION VALUE SHOULD BE VERY DUE TO SOIL RESISTIVITY OF
DIFFERENT AREA LAND SOIL. SUPPOSE IN NEAR SEA AREA GOA OR
OTHER THIS TYPE OF PLACE EARTH RESISTENCE VALUE SHOULD BE
EXCELLENT DUT TO HIGH MOISTURE & SALT WATER.
SO WE CAN ACTUAL MARKING THE RESISTENCE VALUE BUT IT SHOULD
BE 0.5 TO 1 OHMS IS GOOD IN ALL ASSPECT & SUFFICIENT GOOD
CONDUCTACE GEETING TO DICHARGE IN LAND.
AS PER INDIAN STANDERED DETAILS EQUIPEMENT EARTHING VALUE
SHOULD NOT INCRESED MORE THEN 11.2 OHMS. (EARTHING VALUE
MEASURE ON EQUIPEMNT IT SELF)
As per IS: 3043-1966, "Code of Practice for Earthing", the
Earthing Resistance shall not be greater than 5-ohms. The
Earthing Resistance of a Power Station shall be not more
than 0.5-ohm while that of a major and a minor substation
shall be not more than 1-ohm and 2-ohms respectively.
The earthing resistance of an industrial substation
should maintain always below 1 ohm. it measured of
resistance between earth plae and natural earth by ohm
meter. when earth resistance is near to zero means better
The household earthing resistance somewhat slight above
1 ohm and below 2 ohm is the tollerable limit, but never
neglect above 2 ohm. the resistance below 1 ohm means more
Based on CPI/CGPA they shortlist the candidates & than
directly start Interview so there is no Written Exam or GD
Only PI.Interview held @ MNNIT , ALLAHABAD On-Campus on
6th,Aug, 2007 & the Questions asked to me by Interview Board
( 4 People) are from HR/SummerTraining/BTP/Subject-core,
POWER SYSTEM & MACHINE. time duration of I/V is about 15-20
Q.1 Name,hobbies & About family background ?
Q2.What u know abt NTPC ??
Q3.Why u want to choose NTPC as ur Carrier's starting i.e
power sector not any other Oragnisation or sector ??
Q1.What is the reason for transformer Noise ??
Q2.Which material is used for making Transformer oil & How u
measure its dielectric strength & Name the test ?
Q.3 Which Machine u will prefer 2 use if flammble gases are
coming out at a place & why ??
Q4.What is relation b/w Transmission Lines & Communication
Q5.What is the maximum capacity Synchronus Machine & total
powerGeneration in our country ?
Q.6 In india Power generation is at 50Hz while in America
its 60 hz ,why so ?? Advantage or disadvantage ??
Q.7 Maximum Generation Voltage in india ?
Q8. What is the Voltage regulation & why its required n how
much is permissible ? & causes of voltage variation ??
Q.9 Why electric shock is feel ?? n in a Electric Train why
we didnt feel that ?
Q.10 Have u seen/ experience of any power plant/ industry
related to the power sector ?
so these are the questions which not too diffcult i
think was asked to me.