Hot Rods Power shear question

I bought a Di-Arco 24" power shear for my shop from an auction and don't even know if it works. My question is that it's a 3 phase unit and I was wondering if I can replace the motor with a single phase of the same frame, HP, shaft size. Or do I need to get a larger HP motor. I do have all that's needed to make a 3 phase converter but I don't want to do this unless I have to.

 

You could replace it with a single phase motor, or you could use a VFD to drive the 3 phase motor off single phase power. As the price of VFDs has come down, a lot of people find they're a cheaper alternative for low HP motors than buying another motor or building a phase converter.

 

Yep, you can. You'll have to slightly modify the control wiring (one less wire) but that should be it unless the motor is reversible.

 

I just looked at a video of a 3 ft Di Acro shear, and it has a face mount motor. If yours has the same, you'll definitely want to go with either a VFD or a phase converter unless you happen to have a single phase motor with the same face mount laying around. Face mount motors are seriously expensive as compared to standard frame motors.

 

I'll have to move some stuff out of the way and craw under it and look.
thanks

 

It's a 3/4 hp 208 volt 3 phase 56.5 frame. there's a micro switch along with a bunch of other switches. Its looks easy to change motor because it's chain driven but I don't know if the other electrical switches need to run on three phase. I guess I'll to get a electrician to look at it. Thanks

 

I've got an electric motor rebuilder guy close to my shop, who is fantastic with the old motors. He's done miracles to burnt motors, switching rotations, finding replacing motors. See if there is one of these shops in your area, they have lots of knowledge that car guys usually don't, and can probably fix you up!

 

You would be surprised how little a 3/4 Hp VFD costs. I would bet you could buy a brand new one for $100 to $150. Much cheaper then rewiring and switching the motor.

Good Luck

 

Well, I bought a 1/4 to 1 hp VFD for $170, Hope it works

 

The VFD is the way to go. I have tried all of the phase converter methods over the years and haven't seriously looked at anything else since I got my VFD.

I currently have two mills, a lathe and a surface grinder that are all 3 phase.

Make sure that the VFD only feeds the motor and that you have the correct voltage to the control wiring. If you fry the control wiring the motor will be the least of your worries.

 

The shear has a plug so it should be ok. I'm going to run the VDF to a receptacle and plug into that. I guess I can use another 3 phase item if I get one in the future by just plugging whichever one I need in. Actually it turns out it will run up to 3 hp if I use 220 volts.

 

Don't wire it so that there's any sort of switch between the VFD and the motor. Opening the circuit with a load on the VFD is a major thing for killing them. The VFD will soft start your motor and provide all the necessary control. With a 3/4 hp motor driving a flywheel typical of a shear, the VFD and the 3 phase motor will give you a lot better setup than what you'd have if you'd changed it to a single phase motor. The typical single phase motor relies on the kick of a capacitor to get it started against a load, and a flywheel is a different type of load as compared to most motor loads. The VFD will have a ramp setting that will allow the motor to slowly bring the flywheel up to speed. In the same situation, if a single phase motor doesn't have sufficient capacitors it can just sit there and generate heat until the internal overload kicks out. With the VFD, you have the best setup possible for running a 3 phase shear off of single phase power.

Oh, almost forgot...... run the VFD off of 220V power if it has that capability. That will have the VFD just loafing along where it will have a much longer life than if it was fed by 120V power.