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# phase AC induction Motor

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2005-2006 » Archive through 20 July, 2006 » # phase AC induction Motor « Previous Next »

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Abhikg
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Username: Abhikg

Post Number: 11
Registered: 06-2006

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Posted on Tuesday, 18 July, 2006 - 01:19 pm:   Edit Post Delete Post Print Post

If i operate a AC induction motor by giving a 3 phase supply and suddenly one phase becomes open, what will affect in the AC motor?

Again, if one phase will become short with neutral, what will happen.

Please help
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Sounded_simple
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Username: Sounded_simple

Post Number: 152
Registered: 12-2005

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Posted on Tuesday, 18 July, 2006 - 01:53 pm:   Edit Post Delete Post Print Post

In my experience the motor will probably stall if under load.
The breaker and/or the motor overload will trip shortly after.

If shorted to neutral the breaker should trip pretty fast.
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Steerpike
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Username: Steerpike

Post Number: 126
Registered: 05-2005


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Posted on Wednesday, 19 July, 2006 - 06:56 pm:   Edit Post Delete Post Print Post

As SS said, it may stall if under load, but under light load it will continue to operate with reduced torque.
If you try to start it from stand-still on only 2 phases, it will most probably destroy the motor.
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Obiwan
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Username: Obiwan

Post Number: 589
Registered: 12-2005

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Posted on Thursday, 20 July, 2006 - 01:45 am:   Edit Post Delete Post Print Post

You lose one third of the power right off the bat when it opens. No load, it would keep going if there's no "brains" behind it.

If there is, it will just shut down. Depending on the load, it will try to keep going. But at some point it will stall out.

But when it shorts, that's hard to say.

(You are asking two questions right?)

What is it shorting to? The motor? As mentioned, the circuit breaker should open very quickly and then it would be an open. But assuming it can't open, well, then you may have a fire, depending on power.

You could certainly burn out the drive components, such as FETs or SCR's.

Melted windings etc... inside the motor.

All depends on what's connected to what, what sort of protection there is, power etc... Very hard to say. Bad, no matter what.
Do Not Hit The Fly That Lands On The Tigers Head.

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