Why stator of induction motor will burnted if its rotor no turned?

[tonygiang]

Hi all !
Why stator of induction motor will burnted if its rotor no turned?
Who explain help me?

Thank very much !

[citfta]

When the rotor is turning it is generating a counter voltage that reduces the current in the rotor.  If the rotor is locked there is no counter voltage and so the current goes so high it burns up the wires.  Here is a link that explains motors and how they work.  You need to spend a lot of time and study carefully the full article.  There is a part of it that explains how the counter voltage is produced.

http://www.electricianeducation.com/theory/electric_motors.htm

[tonygiang]

Thank you very much !

[tonygiang]

Hi citfta !
But I thing that : when rotate the rotor , its current no link over stator . If the rotor blocked (no rotate) , its shorting current generate very big counte-magnetic field and link over to stator , make the coils over heat and burned it. How do you thing ?

Tonygiang.

[citfta]

You have it backwards.  When the rotor is moving is generates a counter voltage in the stator which reduces the current in the stator windings.  If the rotor is locked there is no counter voltage and so the current will go high enough to burn out the stator windings.  You need to spend a lot of time studying the link I gave you.  There is a lot more going on in the operation of an electric motor than most people realize. I worked on them for over 50 years.

If you want to prove what I am saying about the moving rotor generating a counter voltage in the stator just remove the rotor and then put power to the motor and measure the current going into the stator.  Then put the motor back together and let the rotor turn and measure the current going into the stator again.  You will see that even with no rotor at all the stator will still draw more current than with a rotating rotor.