Soft Start Control

[cadman1957]

Hello I am new to this forum and hoping someone can answer this queaton. I just put a new motor on a large woodworking jointer. It was orginal a 3-phase, 3hp motor but I need to chnge it to single phase where I am now. The new motor is a 3hp 3450 rpm wired to 220 volt. When I throw the switch on the new one the belts squeal and appears to be alot of torque on the motor. Is there a way to spin the motor slow and then build it up to speed?
Thanks in Advance,
Dale

 

[ozmosis]

depending on the type of motor and the ratings for voltage, you could fit a low cost VFD that takes 1ph 230v in and outputs 3ph 230v out and put this in line with the motor. The VFD will have an adjustable ramp time and variable speed of course but this could be set to 50/60Hz.
It might be a easier way than changing the motors etc.
However, check the motor if suitable.

 

[jraef]

Some single phase motors can be successfully soft started, but very few mfrs still make and support single phase soft starters because of low sales. I would do it with the small VFD and go back to the original motor as ozmosis suggested. It will cost you less in the long run. A 3HP 230V VFD that can accept single phase input and give you 3 phase output will likely cost around $250, maybe less on fleabay. A 3HP single phase soft starter will cost you the same or maybe $10 less, but then you have to buy a new motor.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[cadman1957]

Thanks for the replies. I traded in the 3-phase motor when I bought the new motor. Do I understand correctly that a VFD control will still work? How will I know if the type of motor I have will work with the VFD? I think the manufacture is Baldor?

Thanks,
Dale

 

[eeprom]

I don't see why switching from 3ph to 1ph would change the motor acceleration. 3hp is 3hp. Was the original motor the same rpm? Why didn't the original motor need a soft start?

EE

 

[LionelHutz]

If the new motor is a capacitor start motor then you could try lowering the size of the starting capacitor.

 

[itsmoked]

And just confirming; you most certainly can NOT use a VFD with your new 1ph motor.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Steven1984]

Fairford Electronics still offer and support single phase soft starters, which will help reduce the issues when starting.

Steve

 

[cadman1957]

I tested the jointer at the shop I bought it from and they have 3-phase and it started smooth but when I put the new 220V 3-hp 3450
motor on it torques the head hard and belt squeals until head comes up to speed. I will get the specifics of the new motor and see if you guys can confirm if soft start will work. Thanks for all your time.

Dale

 

[cadman1957]

Is this the soft start you had in mind? Does the application matter?

Thanks,
Dale

 

[ozmosis]

eeprom makes a good point. Maybe check the belts.

The HFE used to be called SPOSS. I have one on my desk as a paperweight and its been with me for many years since Ray Bristow (Technical Director of Fairford) gave it to me as a sample. This would work.