Answers were Sorted based on User's Feedback
Answer / anand
bwlow 1 ohm
|Is This Answer Correct ?||35 Yes||7 No|
Answer / anilram
for perfect earting it should be zero ohms. for pratically
at site it 1-5 ohms . in large substations the should be
below one ohm
|Is This Answer Correct ?||22 Yes||3 No|
Answer / seth roosevelt dabri
it is between o - 0.5 ohms in large substations the should be
below one ohm
|Is This Answer Correct ?||10 Yes||2 No|
Answer / sreenu
IT'S ABOUT THE RANGE LIKE 0.7 TO 0.8 . DUE TO COMPONENTS
PRESENT IN EARTH.
|Is This Answer Correct ?||16 Yes||10 No|
Answer / jan
No fixed rule. depends upon site. better keep it as low as
possible else high touch/step voltage
|Is This Answer Correct ?||6 Yes||2 No|
Answer / syed qamar abbas
The ideal value of earth resistance allowed is 1 ohm or less
for equipment's body earthing or grounding like generator,
Main distribution boards , motors etc. On other hand the
value of earth resistance allowed for lightning protection
system is 10 ohms (ideal)
|Is This Answer Correct ?||8 Yes||5 No|
Answer / bilal descon
1 ohm is ideal, but thats depend from place to place.
Near desert ares its more up to 20 ohm, but normally
betweem 0 to 25 ohm is acceptable
|Is This Answer Correct ?||10 Yes||8 No|
Answer / sethu
perfect earth value - 1.5 ohm
lighting arrest earth value - 1.7 ohm
|Is This Answer Correct ?||2 Yes||1 No|
Answer / anubhav gupta
Resistance of earth should be zero but it can't possible. however, according to NFPA &IEEE the resistance of earth is 5 our less
|Is This Answer Correct ?||1 Yes||0 No|
why the CT ratio secondary is always divided by 5 for eg( 75/5,80/5,50/5)
For refrigerators the motor current is raised beyond its rating on both conditions when the voltage of the system is more(say 270v) than the rated voltage(220v) as well as when the voltage of system is less(say 160v) than normal voltageof 220v, why explain?
When we use PT in HT Panel why the ratio is 11Kv/√3/110v/√3 please explain briefly with suitable formula?
how can we calculate the ampacity of the electrical wire/cable. and what are the factors must be considered. pls. elaborate.
why v/f ratio to maintain constant in speed control of induction motor?
what is negative current?
How delta connection in the primary of distribution transformer reduces harmonics?how delta connections reduces harmonics?Please answer me...Hope that question is correct.
What is the need for checking knee point voltage for CT's?
Show Details FROM:Muhammed Ikram TO:email@example.com Message flagged Saturday, June 4, 2011 10:07 PMMessage bodyHello all, i want to ask a question to all of you that what is VMM (voltage monitoring module )? how it work,s? i heard somewhere that it compare 1 phase voltage to other phase voltage. but there is also some setting on it. how to set it,s setting. please tell me briefly. Thank,s and Regard,s. Muhammed Ikram.
How to distinguish whether MCB is DC or AC looking at it physically
How can we decide cable size from HT panel to Transformer? Please give you reply with some examples.
3 phase =440v single phase = 230v 2 phase =?