Question { Ashok Leyland, 97472 }

what is the difference between megger and earth tester?

Answer

Actually megger is a brand name and tester called
insulation resistance tester which measure the Insulation
resistance and earth tester is measure the impedance of the
earth circuit.

Question { Bharti, 6393 }

what are the types of basic earthing?and why we are doing
that?

Answer

There are two types of earthing 1)earthing:Earthing
arrangement may be used for protective(overcurrent
protecctive device provide protection against inderect
contect and overcurrent)or functional(correct operation of
electrical equipment or to permit reliable functioning of
electrical installation. & 2)equipotential bonding:to
minimize the risk associated with the occurence of voltage
differance between exposed conductive parts of electrical
equipment and extranous conductive parts.

Question { 12104 }

why autotransformers are not safe for supplying low voltage
from a high voltage source?

Answer

An auto transformer can could fail in such a way as to have
a primary voltage secondary and such condition cause a
damage or injury.

Question { 14171 }

how we have to calculate the short circuit current for
33/11kv 2mva, 7.5% Z, Transformer primary side breaker and
secondary side breaker short circuit current for both sides?.

Answer

Short Circuit Current=mva/z=2/.075=2.67MA,rating of
transformer is always same for primary or secondary

Question { 14171 }

how we have to calculate the short circuit current for
33/11kv 2mva, 7.5% Z, Transformer primary side breaker and
secondary side breaker short circuit current for both sides?.

Answer

Sorry I give a wrong answer above and I realize latter
on.correct answer is
short circuit current=mva/v*z=2000000/33000*.075=808A
or .8kA

Question { BARC, 10394 }

why the earth terminal in three pin top is longer than rest
of the two terminal and of bigger size?

Answer

because when we pull out the plug the contect is disconnec
is earth.