3 phase motor help ?

[jules27]

I am I right (or wrong ) in thinking that a single phasing motor could Carry on running , working to an extent ?? or would it just trip ?
It seems to be running at lower Amps now?

Many thanks

 

[netblindpaul]

I have seen 3ph motors continue to run after loosing a phase.
But, not restart after stopping.

 

[jules27]

Ok thanks,
seems strange as it works to an extent but it has started afte being stopped .....

 

[netblindpaul]

jules,
Have you lost a phase or have you another issue?

 

[johnboy6083]

3ph motors will carry on running as NBP said, however they will be noisy, and will probably vibrate more than usual. what is the motors job? ie, could a load attached to the motor, cause it to get eenough kinetic energy in order that it may start on 2 phases?

 

[jules27]

Not sure will have to look 2moro will check all fuses on main isolator , All WAS fine working well will have to check 2moro .Will post back then

 

[johnboy6083]

work in reverse mate. How would you getthe motor to work? what would you need. If it isnt there, then youve got your problem

 

[Knobhead]

Just to correct, a lightly loaded 3Ph motor can start on 2 phases. If it does start it’s 50/50 which way it goes.
Correctly set O/L’s should protect the motor.

If you get an earth fault on the failed phase, all sorts of weird things can happen.

 

[Engineer54]

Ok thanks,
seems strange as it works to an extent but it has started afte being stopped .....

If the motor is single phasing, you would most certainly know all about it..lol!!

As Tony has stated, i've known a few lightly loaded motors to start, if haphazardly, with just two phases, but you wouldn't want them to run for too long in that condition, as it would be very clear, that something was very wrong!!!

This motor and it's associated controls, needs to be looked at and sorted!!!

 

[Knobhead]

This is when motor faults get to be fun, NOT! A broken phase winding with the earth to one end.

View attachment 8110

The motor will start in the right direction and run as rough as a dog until the O/L’s trip

 

[jules27]

Thanks for your replies guys its all usefull info for me . Turns out it's a MECHANICAL fault . Although this fault had caused us a to lose a phase this morning (but that tripped the O/L).

many thanks

 

[ipf]

Suggest you test the windings and overload settings before re-using. Overloads should have done their job but looking at your earlier posts you can't be too careful.

 

[jules27]

Will check again although it did work yesterday , cheers