Answer / snipper

motor speed will decrease..noising will increase.. suddenly
current value will rise..it may affect windings..

Answer / derek

Answer 9 is best so far. Normal cause is undervoltage (brownout) causing contactor to partially drop out and contacts weld. Often nothing happens until motor is stopped but welded contact lets current flow and then motor burns (if motor lightly loaded). We are all assuming that problem starts outside the motor. It also happens that an open circuit happens in the motor and then the other two phases burn.

Answer / jcdpk

Yes, if you have a 3Phase motor and it goes single phase on
you the remaining two phase will draw up 173% more. Usaully
the motor will burn up and will need replacement or repair.
The motor will heat up more then then its rated current,and
will not function properly.

Answer / tarique

then speed of motor lowers down therefore rotor windings or armature windings get burn if motor is running under this condition for a long time

Answer / shriprasad

If single-phasing occurs when a motor is rotating, the torque produced by the remaining two positively rotating fields continues to rotate the motor and develop the torque demanded by the load. The negatively rotating field, the field associated with the lost phase, produces currents in inductive loads resulting in voltages in the faulted leg of the three-phase supply. These voltages may be nearly equal to the phase voltage that was lost.

Answer / bhupendra kumar

total flux in the air gap has to be maintained always.if one of the phase is disconnected,more current has to flow in the windings so that the flux in the air gap is maintained constant.this will defintly burn up the windings of the motor.

Answer / sharma sam

three phase supply is carried by three line conducter.single phasing means one out of line three conducter stop working due to some fault.Line wire broken,Terminal contacts become loose are reason for the fault.as the result of which other two line conducter start drawing more current from supply.this uneven distribution in current damage the insulation of winding and cause the flactuation in torque produced.

Answer / raj mohan singh

The following are the
effects of single
phasing:
1) Due to single phasing
the current in
the remaining two phases
increases
and it is approximately
2.4 times the
normal current value.
2) Single Phasing reduces
the speed of
the motor.
3) The motor becomes noisy
and
starts vibrating due to
uneven torque
produced in the motor.
4) If the motor is arranged
for
standby and automatic
starting then
the motor will not start,
and if the
overload relay provided
fails to
function then the motor may
burn.
5) The windings will melt
due to
overheating and can give a
fatal shock
to the personnel.
6) It may cause overloading
of the
generator.

Answer / preecha

the motor will burn out,all types of winding connection
will be affected

Answer / rajesh sharma

first. if motor conected in star than the winding which one
not gating phase it remain but other two winding which got
their phase they come in series and they burn becaz they
got 415v on the behalf of 230v. time is depend on load if
motor run on full load than motor burn in 15 to 20min if
motor run on half load means50% than its take more time as
well as incase of delta if R phase blown than Bphase of
winding burn becaz RandYphase winding come in series and B
winding got double phase so it burn. thanks for read

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