normally speaking, earth and neutral is having the common
point at generating stations.
But neutral is treated as the "return" path of the supply.
But when we are transferring supply to a long distance , it
needs 4 conductors, 3 for phase and the last one for
neuatral(return).So it is getting expensive ,
so normally we are earthed at the generating stations and
only taking 3 condutors till it reach the i/p of the
Distribution transformer(i/p is delta) and from the
secondary(star) we are starting neutral(altogether 4 wires).
And this neutral is earthed there.
it s a frequently asking interview question..
earth is defined as the protective circuit .
and neutral s defined as the current returning circuit.
ground wires are connected to all electrical equipments
metal body. if there s any fault in equipment , it may
cause current on its body. earth wire connected to metal
body carries this fault current to earth and decreasing the
effect of shock. for this , the earthing should be perfect.
AC is sine wave, ie voltages become zero in each cycles.
this zero voltage is referred as neutral. in 3 phase
transmission system, the voltage disbalance between lines
may leads to flow some current through neutral. due to this
reason neutral s earthed in all substations.. thank u..
neutral is a reference point and a return path for any
"live" circuit. Earth is an energy ZERO point.
When ALL phase has balanced load, neutral should be ZERO
volt in respect to earth. Becareful the word "balanced",
which means, when there is an unbalanced phased (due to load
or otherwise), the neutral will no longer be ZERO volt in
respect to earth. When there is more than ZERO volt between
neutral and earth, then there will be current flow through
these 2 points (leakage).
Even for most of the time, neutral and earth has ZERO volt
between them; they should never be connected together or be
first of all we should clear in the terms of earth and
neutral. earth is always zero potential and neutral is the
reference point of a.c system.i.e neutral is also in the
zero potential but not always.
two types of earthing is available
1. neutral earthing
neutral earthing is used for equipment safety and equipment
earthing is used for human safety.(body of the equipment is
connected to earth.so during fault time, the fault current
flows through this)
so earthing is only for safety purpose.
but neutral is a returning path to an alternating current.
Explain What will happen when direction of field current is
changed (i.e, field excitation is reversed) in the
2) Synchronous Motor
3) D.C Generator ( Shunt or Seies )
4) D.C Motor ( Shunt or Seies )