Motor question

[Guest55]

......a load of technical stuff

just the man , got a motor question for ya.
what would happen if 1 phase went down while 3 phase induction motors were running at the time ? ( with regards to the motors )
its part of my assessment for overload protection for a 250A panel board ( bs 88 fuse or adjustable mccb )
thanks.

edit ; apologies for putting this in a sticky - just realised.
welcome it being moved to a more suitable home.

 

[Marvo]

Relocated as per request.

 

[Silly Sausage]

Re: Motors

The quick answer is, it would carry on running.
The rotating field would still exist on 2 phases.
Efficiency, torque etc you'd have to do the maths (happy days! )

 

[Guest55]

good job i've got a man on the inside clearing my crap up lol - he knows who he is.
thanks archy.

 

[Silly Sausage]

good job i've got a man on the inside clearing my crap up lol - he knows who he is.
thanks archy.

???????!!!!!!

 

[Guest55]

Re: Motors

The quick answer is, it would carry on running.
The rotating field would still exist on 2 phases.
Efficiency, torque etc you'd have to do the maths (happy days! )

would any damage occur to the motors if this happened ?

 

[Guest55]

???????!!!!!!

a joke with marvo moving my post , then me asking him to move your following post so you dont look like some loser talking to a post thats gone.
basically :-D

 

[Silly Sausage]

a joke with marvo moving my post , then me asking him to move your following post so you dont look like some loser talking to a post thats gone.
basically :-D

It's alright, I'm used to it!

 

[Knobhead]

As Archy says if you loose one phase it will keep running if on light load. The overloads will stop it on phase failure after a short while. If the motor in unloaded it may even start up again, but it’s a 50/50 chance which way it goes. With just two phases you effectively have single phase so there is no phase rotation other than what would be caused by induced phase shift in the windings.
I’ve got a drawing I could post but it’s not possible at the moment.

 

[Knobhead]

As to damage, if the O/L's don't trip, the motor will burn out.

 

[Silly Sausage]

Ahhh!! The 2 phase motor question! Which direction?!
Where is that thread? Happy days...

- - - Updated - - -

As to damage, if the O/L's don't trip, the motor will burn out.

Why? ...................................

 

[Guest55]

As to damage, if the O/L's don't trip, the motor will burn out.

cheers
the motors power combustion fans for a gas fired incinerator , and are ( i think ) electronic inverter controlled.
if this has any bearing ?

 

[Marvo]

If the motor is run by a drive or an inverter then there should be protection against missing phase and overload etc built into the drive. You may need to set up the parameters in the program so you'll need the instructions if you're not familiar with that particular drive. Most of the bigger manufacturers like ABB, Delta, Emerson etc have them downloadable as pdf's from their websites.

 

[Knobhead]

Just follow the destructions.
To be honest Biff I'd be surprised if a combution fan was on an inverter.