Earth resistance of earth pits shall depend on the terrain
in which the same is provided. Accordingly, based on soil
resistivity data of the location, no. of earth pits is
determined to ensure Grid earth resistance value below 5
Ohms for electrical grids,
For solidly grounded neutral of transformers, resistance
between Neutral & Body earth as well as panel earth shall
The earthing resistance indicates the easiness of providing
a path. It should be as low as possible. Different
countries having standard values. In india, for commertial
applications its <1 ohm, and for railway its< 0.5 ohm.
for air craft and ships temp. earthing <10 ohm.etc.
even any earth pit is concidered every earth pit should have the value 0ohms.but in rare cases u will get that value,more over will come 0.3to 0.9,there fore the earth pit value should be less than 1 ohm.ok
keeping in view of parallel operation which of the 3 phase
transformer connection are possible?
a)delta-delta to delta-star b) delta-delta to star-delta c)
star-star to delta-delta d) delta-star to star-delta
In a three phase transformer(delta/star connected)when i
touch one end of the bulb in any one phase and other end to
earth..will the bulb glow or not..if not why?..i'm touching
the bulb in star connected side...