Motor Reversing Cause

What is the motor function, pump, blower etc? Motors if being caused to rotate in the reverse rotation by some external force will continue to do so when the motor starter engages. Pumps in parallel one with bad check valve. Blowers in parallel in system if both are not started at the same time.

i think as you know maybe that when 3 phase motor loss one phase due to some reason and if the winding is strong enough to bear the load then motor runs in a reverse direction.

if some one think i am not right plz tell me

That can happen.

The motor runs a lot hotter and consumes a lot more current on the two phases left.

Its often very noisy as well......

Usually due to a burnt or loose contactor contact or similar.

thanks for Ur comment

actually that is motor operated Valve.( Actuator)

that contain in 3 phase ,single cage type motor, PCB electronic circuit, 110V contactor. ( not relay)

electronic PCB circuit, that will be produce 110V output for contactor coil to energize and de energize.(2 contactor for Close and Open) when command is given . Once command is given,(either open or close) electronic circuit is take action and give output of 110V for energize that contactor coil. contactor coil is energize, aux contact will be taking for 3 phase supply (U V W ) to motor terminal . U V W.

Scenario:

i found out , when give close command , 110V is coming from PCB and close contactor is energizing, Aux contact that from these contactor will be take 3 phase supply (U V W) to motor terminal and motor was run for close action to that valve. after that nearly to reached valve is shut,( at the time, torque will be rising up for fully shut to that valve). motor rotation was changed and this contactor was continuous energized and valve will be open back.

so i was issued for that contactor to replacing another one. ( same model contactor)

after that OK.

so i want to kn0w, that contactor is energizing why motor was reversing didn't change yet another phase shift. am i right ? if that contactor contact due to loose for one phase , then phase shift will be can change or that stator winding producing magnetic flux cutting by rotor will be less and abit strong rotor magnetic flux will occur this during then rotor direction will be change . that wht i read and then (i suspect for that contactor, so i was changed.now OK ). So if one phase lose, that 3 phase motor will be change another direction ? during increasing load or another reason. let me get ,pls.

thaks,

thaks,

i have experience that when 3 phase motor loss one phase the motor runs in a reverse direction

ok , i got it. thank you .

I have never actually analyzed why, except to notice that if the mechanical motor load is more in one direction than the other, the motor turns in that direction, the direction of least resistance.

Don't forget that with only two of three phases connected, there is no proper "directional turning moment" in any particular direction anymore.

If you had the motor without any mechanical load, spun it by hand and quickly connected only 2 phases, it would most likely continue in the direction you spun it.

Same with the opposite direction.

It only has two fields pulsing 120° out of phase.....

Its that simple.