Edger conversion form Gas to Electric

[Dewey]

I have a Thomas Edger that is gas powered with a 8.5 HP Honda.
Want to convert it to a 10 HP Electric single phase.
I can't go 3phase because my sawmill is run with a phase convertor.
I don't have enough electric power to run another.
With gas there is a clutch that engages when RPM is up there.
With electric the RPM are instant... DO you think there would be a problem or should I incorporate the clutch somehow. Or should I not use a clutch ( I'd prefer)

[charles mann]

Use a single phase motor speed control and bring the rpms up gradually. 

[Bruno of NH]

I wouldn't think it would be any different than my single ph unisaw cabinet table saw 
It has just on and off
The Woodmizer eg 100 is single ph , I don't know if it has speed control of the arbor 
The belts do

[Southside]

I have a 7.5HP farm duty motor on my 725, just push the start button on the contacter and off she goes, zero to zoom instantly.  The only thing you need to make sure of is that you have enough amps available for the start up load.  

[PAmizerman]

I would try it without first 
You can always ad a soft starter later.
You could also use a VFD. There's settings in the parameters for ramp up and coast down 

[scsmith42]

Here is what may be your best solution.

1 - get a good, used 3 phase electric motor for your edger.  My Woodmizer twin blade edger uses 15hp and that's marginal for 8/4 oak.

2 - use a VFD (Variable Frequency Drive) to convert from single phase to 3 phase for the edger.  VFD's also allow you to bring the speed up slowly.

This way you can benefit from a larger 3-phase motor and have a soft start system to boot.

[muggs]

I think I will chime in here. A few points. A VFD will not work on a single phase motor. If you are satisfied with the power of your 8.5 hp gas engine. A 5 hp electric motor would be about equal. I have 15 and 20 hp single phase motors but the shipping would be a killer. How big is your service coming in?

[SawyerTed]

If you can figure out a 3 phase solution, you'll get better performance and lower amperage draw.

Full Load Current on a 10 hp single phase motor will run around 100 amps at 220 volts.  

FLC on a 3 phase 10 hp motor will be 28-30 amps at 220 volts. 

Depending upon the service entrance amperage 100 amps could max out the service.   That's especially true if your mill is already on the service. 

Even if the motor never reached FLC, half is still 50 amps on the single phase.  

Switching to lower hp than 10 hp 3 phase would be the alternative.  FLC on a 5 hp 3 phase is 18-20 amps at 220 volts. 

Smaller motor, smaller amperage will make wiring less expensive.  

[Southside]

Muggs - what did that 20HP come off of?  Didn't realize you could get a single phase that large. 

[PAmizerman]

@muggs they make a single phase to single phase VFD

They are just crazy expensive 

[Southside]

Browsing around on CL just now I came across a 250HP, waterproof, 3PH, NOS, motor for sale in Richmond.  That will likely handle 8/4 oak just fine.  :D

[muggs]

PAmizerman I learned something new. Southside, yea 250 hp ought to turn the blades 8) The big motors are heavily modified 3 phase motors, I have a small motor shop. I will see if I can put up a video.Bob Motor July 2020 - YouTube

[bushhog920]

Look into Soft starters.

 

 

[Southside]

Ok Muggs - you got me.  HOW did you do that?  Is it economical to do?  What is the size limit on such a modification?  What voltage motor do you need to start with?  You have absolutely peaked my attention. 

[Ianab]

Soft starters would get around having marginal power supply to start a large motor.  A motor that needs 20A to run, might need 40 or 50 to get it started. Maybe only for a couple of seconds, but long enough to blow a fuse or brown out the power. Soft starter ramps up the current slower, might take a couple more seconds to spin up, but you dont have that initial spike, and should be OK running a 20A motor on a 20A circuit.

[muggs]

Ok Muggs - you got me.  HOW did you do that?  Is it economical to do?  What is the size limit on such a modification?  What voltage motor do you need to start with?  You have absolutely peaked my attention.

Southside, this is the most I can say. The 3 phase motor needs a partial rewind. A lot of components are added. Voltage needs to be 230V. Size limit depends on the size of your incoming power and my ability to lift it. These motors will also work as a phase converter with a slight change in wiring in the junction box. All motors can't be converted, I need to see inside of it. cost is about $100 a horsepower. Biggest drawback is shipping. I think I live in the wrong state. :'(

[Southside]

Is this something you figured out?  Seriously I am amazed at this.  

[muggs]

Is this something you figured out?  Seriously I am amazed at this.  

First. I have background in electrical. It was several years in the making. Studying other peoples patents. Making every mistake there is. Writing down the mistakes. Keep moving forward. Finally success.

[Sod saw]

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muggs,  I think that I may be confused (normal for me).

In your video, you started two machines.  The one with the two display readouts, , ,  was that the motor in question?  Was the top display showing voltage?  What was the bottom readout showing?


.

[muggs]

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muggs,  I think that I may be confused (normal for me).

In your video, you started two machines.  The one with the two display readouts, , ,  was that the motor in question?  Was the top display showing voltage?  What was the bottom readout showing?


.

On the displays, the top one is voltage, bottom one is amperage. Yes that is the cutterhead motor ( the modified motor) The second motor I started is the feed motor, no connection to the cutterhead motor.

[Sod saw]

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Thanks for clearing up the display question.

Which motor is the one that you changed from 3 phase to single phase?


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[muggs]

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Thanks for clearing up the display question.

Which motor is the one that you changed from 3 phase to single phase?


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The main motor, the one that powers the cutterhead   5 HP

[Sod saw]

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Let me see if I understand this.

A normal single phase 5 hp motor at 230 Volts will draw in the neighborhood of just under 30 amps operating full load but not locked rotor.  I will not talk about inrush here, for now.

A normal 3 phase 5 hp motor at 230 volts will draw in the neighborhood of about 15 amps operating full load but not locked rotor.

Your converted 3 phase 5 hp motor operating on single phase 230 volts is drawing just under 7 amps with full load but not locked rotor.        According to your video.

If I understand correctly, the cost to change from 3 phase to 1 phase; a 5 hp motor is about $500, plus the initial cost of the 3 phase 5 hp motor (or tool with that motor).

Please correct me if I am off base here.   My impression is that a small 3 phase motor might be less costly to replace with a single phase motor but a larger motor might be less costly for you to modify it compared to changing over your (our) electric service entrance equipment.

If your ratio of current draw "savings" follows thru as horse power increases, we could also save on wire costs due to smaller wire gauge, circuit size, etc.

Now to the subject of locked rotor.  What is your converted motor (branch. circuit) current draw with a locked rotor?  Will your new control box shut down the motor if the rotor becomes locked?

OK, enough questions for now.  thanks


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[muggs]

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Let me see if I understand this.

A normal single phase 5 hp motor at 230 Volts will draw in the neighborhood of just under 30 amps operating full load but not locked rotor.  I will not talk about inrush here, for now.

A normal 3 phase 5 hp motor at 230 volts will draw in the neighborhood of about 15 amps operating full load but not locked rotor.

Your converted 3 phase 5 hp motor operating on single phase 230 volts is drawing just under 7 amps with full load but not locked rotor.        According to your video.

If I understand correctly, the cost to change from 3 phase to 1 phase; a 5 hp motor is about $500, plus the initial cost of the 3 phase 5 hp motor (or tool with that motor).

Please correct me if I am off base here.   My impression is that a small 3 phase motor might be less costly to replace with a single phase motor but a larger motor might be less costly for you to modify it compared to changing over your (our) electric service entrance equipment.

If your ratio of current draw "savings" follows thru as horse power increases, we could also save on wire costs due to smaller wire gauge, circuit size, etc.

Now to the subject of locked rotor.  What is your converted motor (branch. circuit) current draw with a locked rotor?  Will your new control box shut down the motor if the rotor becomes locked?

OK, enough questions for now.  thanks


.Lets see if I can clear up a few things.1.. the price includes the motor. 2.. I don't test for locked rotor. My service is not big enough. I would just pop the breaker. The 5 hp motor in my demonstration was the largest motor I had on a machine. I would not build a 5 hp motor. There is no advantage to it. Just buy a single phase motor. 3.. My controll box will not shut down the motor, that is the job of the magnetic motor starter overloads and now I can't type anymore.

[Southside]

Muggs, whatever magic you have figured out there I sure hope it has paid you well and it lives on for a long time.