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Question
What happens if a three phase induction motor is suddenly
single-phased while running? Which type of winding
connection will be affected?
 Question Submitted By :: Malini
I also faced this Question!!     Rank Answer Posted By  
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 1
when three 3 phase motor is suddenly single phased .
it will giving sound and its speed lower down. it
may also burn . and mcb or proction will come in
action. because current will rise very high in this
condition
 
Is This Answer Correct ?    55 Yes 12 No
Rishav
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 2
Motor is running as a single phase motor with lower speed
and creating noise. In this situation it will drawing higher
current. If it runs for long time then insulation may get
damage and ultimately burnout the winding.
 
Is This Answer Correct ?    55 Yes 6 No
Sanjib Pramanick
 
 
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 3
the motor is runing as high speed. the 1 phase was going
tothe motor , the motor winding is burn.
 
Is This Answer Correct ?    7 Yes 31 No
Ponraj
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 4
If a three phase motor is suddenly single phased, nothing
will happen to the motor. Perhaps the motor will coast down
to stop. Single phased means only one phase out of three is
connected to the motor, and since the neutral is never
connected to a three phase motor, there fore no current
will flow into the motor and hence motor will stop as usual.
 
Is This Answer Correct ?    18 Yes 81 No
Raj
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 5
#4
Usually when talking about "single-phased" motor, it means
that two of three phases are connected. In these cases, the
motor will slow down, and the phase currents for the
remaining phases will be increased. I don't know how much. I
am also not sure if the overload device would cut-off the
motor from power supply. Unless problem is not noticed, the
motor will most likely burn. When the motor is opened, you
should be able to see that 2 of the 3 phase windings are
black, and one is good looking (if motor is Y-connected)
 
Is This Answer Correct ?    14 Yes 13 No
Stefan
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 6
if 3 phase motor is suddenly single phased while running
then two phase will supply current to the motor, but it
will draw more current from the main supply,and the winding
will burn out
 
Is This Answer Correct ?    30 Yes 1 No
Arvind
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 7
Three phase motor suddenly runing single or two phase.Motor
will get over heat and giving noise.this case if we have
protection like breacker it will trip other wise motor will
burn out
 
Is This Answer Correct ?    16 Yes 2 No
Syed
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 8
If protection is proper then it will operate and stops the
motor. If there is no protection which is the normal case
in LT motors, then winding will burn there are two diffrent
pattern which will apear depending on the type of winding
connection i.e. delta or star.

You will find most of the winding failure in LT motors
happens due to single phasing.
 
Is This Answer Correct ?    8 Yes 1 No
Rahul
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 9
If a three phase induction motor is suddenly single-phased
while running, no distinct change will happen if it is
running under noload condition. You will just hear a
hunting sound and the the motor will continue to run with a
slightly lowered speed and increased current, but if the
motor is running under loaded condition it will stop down
and take excessive current due to single phasing and the
protection circuit will trip, if protection ckt is not
installed the motor will be ultimately burnt due to
excessive locked rotor current.
And note: This experiment is tested.
 
Is This Answer Correct ?    34 Yes 2 No
Rajesh Shah
 
  Re: What happens if a three phase induction motor is suddenly single-phased while running? Which type of winding connection will be affected?
Answer
# 10
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
 
Is This Answer Correct ?    3 Yes 10 No
Rajesh Sharma
 

 
 
 
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