Help me design an electric log splitter

[nathon918]

cheapest phase converting 15hp VFD I have found thus far:
MA7200-2015-N1

the vfd in your link states 3 pahse input...
why dont you just get a static phase converter? theyre cheaper than a vfd...

 

[blades]

Static phase converter, 1/3 power loss. other than than that work fine, I ran a couple of them at my previous shop location , no 3 phase there, $1500 min for power company to drop a line in , which was at the back of the building less than 20 ft away.
That could be a viable option for him.
I actual ran multiple units from mine as long as you start the largest one first, and do not exceed ratings. they work ok for continuous run equipment no good for a compressor. They do not seem to be able to handle that high load restart. They might have changed some since I had mine as that was almost 20 years ago.

 

[cstamm81]

Well my thought is the vfd is a much nicer solution, and I hate the 1/3 power loss. Could just buy a single phase 5hp motor in that case. The vfd I linked showed the ability to take a single phase input on another site, but with half the rated output.
Hddnis, I believe I found what you were talking about, a vfd rated at full output with a single phase input. PC1-75

 

[Hddnis]

Well my thought is the vfd is a much nicer solution, and I hate the 1/3 power loss. Could just buy a single phase 5hp motor in that case. The vfd I linked showed the ability to take a single phase input on another site, but with half the rated output.
Hddnis, I believe I found what you were talking about, a vfd rated at full output with a single phase input. PC1-75

Looks like it should work to me. I'm no expert on VFDs by any stretch, I just researched them a bunch because I was looking to power some three phase stuff in my shop, but then had to put that project on hold.

I don't know your timeline, but if you wait you can get single phase motors for cheap. There is one in the next town over from me that is single phase 5hp for $125.00 It'd take that much more at least to ship it to you or I'd offer to pick it up for you.



Mr. HE

 

[cstamm81]

Talked to the MTE hydraulic pump company today, guy thought I may be pushing it running his 22GPM pump on 7.5HP electric. He did not seem very confident though. I talked to a VFD place today, they wanted to sell me a 20HP VFD (derated to 10HP with single phase input) for about $1000. Stated it should have a 100A breaker used with this VFD!!!! I do not really understand that, as even a 10HP 3 phase motor will draw less than 30 FLA. He stated the manufactures always call for a large breaker, and this VFD does put out 60A if used with a 3 phase input. It just seems like I am asking for trouble putting that large of a potential load on my 200A home service panel.

Getting more confused.... I really wanted to go to a 22GPM pump for quick cycle times. I do not want to go with too small of a motor and not be able to run the pump properly. I am not forced into using the 7.5HP 3 phase motor I purchased, I could go bigger or smaller if need be. I really am sold on electric, but for what this could cost I have to at least start to think about a gas engine, used ones are plentiful and relatively cheap. Not chapping out yet, but need to think this through.

 

[Hddnis]

Sounds like you are getting information overload more than anything. Don't worry, I do that too, tons of research on a new idea and then I get more confused. Give your brain a little time to chew on it and it will start to fall into place.

I think the VFD he was trying to sell you was too big. For less money you could get a new single phase motor and greatly simplify everything.

7 5 HP Electric Motor for Compressor 184T Frame 3450 RPM 1 Phase Leeson | eBay


7 5 HP Single Phase Replacement Electric Compressor Motor 213T Frame 230V | eBay

To use your motor look into a phase converter. Most of the following will run 7.5hp, but only if you are not loading it heavy. Some have built in motor starters and some lack that. Most seem to have free shipping.

Rotary Phase Converter AR10F UL UL 10HP Heavy Duty UL Listed Floor Unit HD CNC | eBay

New 10 HP Rotary 3 Phase Anderson Converter | eBay

7 5 HP Rotary Phase Converter | eBay



Mr. HE

 

[Hddnis]

If you go with the 16gpm pump and the ram you talked about your cycle times are going to be under 10seconds for 24" stroke. If you only go with 18" stroke your cycle times will be less than seven seconds. That is pretty good cycle times overall and will pile up the split wood nice and fast. You'll also have decent tonnage rating, not much out there you won't be able to split.




Mr. HE

 

[blades]

Unless you are planning to shut off the motor every 10 minutes or so, a compressor rated motor is not the type. ( really hard on converters as well) Continous duty is the type. Rotary phase converters have less loss than the static type as they use essentialy another motor to generate the third leg. In either case they must be sized at or preferable above fld amp. of the motor selected for use. In the case of a rotary converter that means it will be equipped with at least a 7.5 hp motor. Stactic converters provide the third leg electronically as such provide a cost savings over a rotary although there is the power loss. During the time I was using mine I never really noticed any significant power loss in my applications. I have a 15hp motor about 10 ft from me as I type this on a compressor, sounds like a rifle shot going off when the magnetic starter closes and the in rush of current hits things. Sure makes customers jump out of their skin. I barely notice it, course I don't hear too well anyway.

 

[cstamm81]

My issue is I can get a good deal on certain motors and VFD's through work, but I am leaving my current position shortly so the motor / VFD decision I am trying to make asap.
The reasons towards leaning towards a VFD big enough to run a 10HP 3 phase motor are: More flexibility if I need to go from my current 7.5HP motor to a 10HP, ability to soft start the motor and adjust speeds, thus adjusting ram speed, better availability of cheaper motors in the future (3 phase vs single phase).
I am aready ahead as the motor I got was cheap. The VFD would be a big commitment, but would open possibilities. I agree with it complicating things, but I have great luck with VFD's at work and the wiring / setting up parameters is pretty easy.
My big hangup on the large VFD is the fact that it wants a 100A breaker as per the manual. If my 7.5HP 3 phase motor only has 20 FLA, I do not know why a 50A breaker would more than suffice. My future design decisions will not be as hasty once I nail down the motor and or VFD purchase.

 

[nathon918]

My issue is I can get a good deal on certain motors and VFD's through work, but I am leaving my current position shortly so the motor / VFD decision I am trying to make asap.
The reasons towards leaning towards a VFD big enough to run a 10HP 3 phase motor are: More flexibility if I need to go from my current 7.5HP motor to a 10HP, ability to soft start the motor and adjust speeds, thus adjusting ram speed, better availability of cheaper motors in the future (3 phase vs single phase).
I am aready ahead as the motor I got was cheap. The VFD would be a big commitment, but would open possibilities. I agree with it complicating things, but I have great luck with VFD's at work and the wiring / setting up parameters is pretty easy.
My big hangup on the large VFD is the fact that it wants a 100A breaker as per the manual. If my 7.5HP 3 phase motor only has 20 FLA, I do not know why a 50A breaker would more than suffice. My future design decisions will not be as hasty once I nail down the motor and or VFD purchase.

your motor only draws 20 amps, but its 3 phase, you have single phase input which would be more than double the amperage needed, plus the power factor aprox. 125%, plus any voltage drop from panel to recepticle, recepticle to motor needs to be accounted for,
the vfd is rated for a 10 hp motor, so 30 amp three phase to single phase, there you have aprox. 60 amp single phase, plus your power factor, then you have aprox. 75 amp draw,

hes telling you what the "ideal" setup should be, for what the equipment is rated for,
not to say that the vfd wont run your 7.5 hp on a 50 amp breaker, but if your maxing it out then you will prob. trip the breaker...

example.
i have a tig welder that is single phase, 230/480v "requires" aprox. 90/45 amp input
i run it off a 480 3phase panel but only use 2 legs, with a 60 amp disconnect which is the "ideal" setup.
now ive run it on 230v with only a 50 amp breaker, (about half of required) when i had to use it at a different location, but i could only get just under half of what the rated output of the welder is...
under voltage/amperage isnt something that most electrical equipment likes...

 

[cstamm81]

I believe if I go with this 10HP capable VFD I will leave all my options open. Say I run the 7.5HP motor and have electrical issues, I can always downsize to a 5HP. It's a lot of cash, but in my opinion should last a very long time if wired correctly and it's kept from any moisture.
If I go with the 22GPM pump and have trouble turning it with the 7.5HP motor, I would then need to see if I could upsize the motor to 10HP or downsize the pump. I believe the resale on any of these components should be high if I had to resell a component.

Does anyone have a good source for power cable, I looked at McMaster today and 3 conductor 4 gauge is salty!

 

[nathon918]

I believe if I go with this 10HP capable VFD I will leave all my options open. Say I run the 7.5HP motor and have electrical issues, I can always downsize to a 5HP. It's a lot of cash, but in my opinion should last a very long time if wired correctly and it's kept from any moisture.
If I go with the 22GPM pump and have trouble turning it with the 7.5HP motor, I would then need to see if I could upsize the motor to 10HP or downsize the pump. I believe the resale on any of these components should be high if I had to resell a component.

Does anyone have a good source for power cable, I looked at McMaster today and 3 conductor 4 gauge is salty!

if you keep the vfd in an enclosure, be careful, they can get hot a burn themselves out, i have one in an enclosure at my work running a 40hp motor, useto have just a built in fan in the enclosure pushing air through it, but it wasnt enough, had to end up installing a water cooled heat exchanger to the enclosure to keep the temp down to 70deg.

as for cable forget mcmaster, theyre WAY overpriced, find an electrical supply house, im in mass and we have many around me biggest being NESCO (northeast electrical supply company) dont know if theyre in PA or not?
get SJ cord its got a heavy covering, and you should be able to use 6/3 for it unless your going big enough to be able to handle the higher amperage if needed, then id go with 4/3
i run 50ft, or 100ft with extension cord of 6/3 sj cord @ 60amp every day no prob.

 

[CUCV]

Seems like way more HP than necessary... My father built one years ago and it only has a 1HP single phase 220v motor. It's got a 4" cylinder and runs 13-14 sec cycle time. He is actually ready to sell it now that we have an electric Supersplit. If you want speed build or buy a SS. Just seems like overkill to run 7.5-10hp to go from 13-14 sec cycle time to 10 sec cycle time.

 

[nathon918]

Seems like way more HP than necessary... My father built one years ago and it only has a 1HP single phase 220v motor. It's got a 4" cylinder and runs 13-14 sec cycle time. He is actually ready to sell it now that we have an electric Supersplit. If you want speed build or buy a SS. Just seems like overkill to run 7.5-10hp to go from 13-14 sec cycle time to 10 sec cycle time.

whats the length of the cylinder??
no load cycle time?
unless its really short, or very low pressure, theres no way a 1hp motor will cycle a 24-30 inch cylinder in 14 seconds, @ 2500-3000 psi
it simply doesnt have enough power to turn the size pump required for that cylinder @ that cycle time...

 

[CUCV]

whats the length of the cylinder??
no load cycle time?
unless its really short, or very low pressure, theres no way a 1hp motor will cycle a 24-30 inch cylinder in 14 seconds, @ 2500-3000 psi
it simply doesnt have enough power to turn the size pump required for that cylinder @ that cycle time...

24" stroke, multi stage pump, no load cycle time, splitters rarely run at 2500-3000psi for very long. Most of the time they are running under 1000psi from my experience....