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  #1  
Old 10-18-2012, 08:26 PM
derekpfeiffer derekpfeiffer is offline
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Default phase converter

I recently purchased an electric forklift on an auction that i wasn't at due to conflicting work schedule and was told that the charger was single phase. Now I'm debating whether to build my own phase converter or purchase one. Wanting peoples thoughts that have built their own. I work at a power plant so have a larger supply of old 3 phase motors...what would I be looking for for a donor motor and other supplies??

Thanks for any info!!!
Doogie
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  #2  
Old 10-18-2012, 08:34 PM
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Maybe a stupid question, but why not get a different single phase motor?
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Old 10-18-2012, 08:44 PM
derekpfeiffer derekpfeiffer is offline
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The converter will be to run my charger. Simply because instead of spending the money on a different charger i could spend the same money on a phase converter and if I run across a deal on a piece of equipment that's three phase it wont be an issue....more versatility....
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  #4  
Old 10-18-2012, 09:02 PM
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Derek, how many amps does your charger pull at what voltage?
You can determine the size of your idler motor from that.
To build a starting circuit you'll need roughly 60mfd of capacitance per horsepower (of the idler).

My converter build was a lot of fun. Having it has been more fun.
I have a hydraulic press, a 5hp compressor and a 22" Clausing drill press that feed off of it.
I have $625 initial investment in the 3 machines; as you know, they were that cheap because 3 phase intimidates most people in my situation so there just isn't much competition.

I had a free idler motor too, spent about $150 for everything else I needed and that includes a better crimping tool I could have done without.
Mine is 7.5hp.

As far as I'm concerned, choosing to build a converter is just a no-brainer and I'm happy that most people don't agree with me.
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Old 10-19-2012, 07:29 AM
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I agree wiith Cutter, build it. I think it will pay off in the long run. Since you have access to a number of motors, I would get the biggest one over what you need for the charger. That way you will have the capacity for other scores down the road.
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Old 10-19-2012, 09:31 AM
derekpfeiffer derekpfeiffer is offline
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Here's the plate cutter...
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  #7  
Old 10-19-2012, 11:02 AM
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Derek, I preface anything I say here with "I don't know jack about forklift chargers" so take everything with ten pounds of salt.
I have no idea how picky that charging circuit is compared to the demands of a driven motor so we'll need to let our betters guide us there.

But if appears to me that your data plate says 21/18/9 amps @ 208/230/480 volts?

What I was shooting for with my converter was an idler motor rating of about 50% higher than the largest driven motor I was planning to supply, i.e., 7.5hp idler/ 5hp compressor.

As for as balancing the voltages between phases, I did not consider it critical for my purposes, so +/- 10% was deemed adequate and that has proven to be acceptable in use.
But again, I hope the more educated will guide you on that.

I've attached a .pdf of the Phase-a-matic boilerplate guide to their line of rotary converters just to provide a thumbnail guide to the general recommendations.

If you want to wade through my project thread on my converter, it is here.
disclaimer: as usual and like all of my threads, it is rather wordy and was written mostly for my own entertainment, there you can anticipate about 90% bullshit along the way to the heart of the matter, as dictated by Sturgeon's Law.

My other motivation is posting my thread was to illustrate that you don't have to know jackshit about phase converters to build your own so long as you have the helping hands of our group for support and reassurance.

edit:
Derek, I finally located the original article I used to familiarize myself sufficiently to begin thinking that I could pull off this converter thing.
The link to author's site no longer works so I converted the html file to a .pdf & attached it below.
The guy does a good job of starting at the bottom & walking you up step by step.
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  #8  
Old 10-20-2012, 06:32 PM
kbs2244 kbs2244 is offline
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That first PIC makes me think that the unit can be switched back and forth from 3 to single phase.

I would get in touch with tech support at the mfg. before going overboard on a electrical to mechanical to electrical project.
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  #9  
Old 10-20-2012, 10:23 PM
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I second the 1/3 phase adjustment, definitely worth a call to the MFG.
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  #10  
Old 10-20-2012, 11:06 PM
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That would be very nice.

But Doogie still needs to build a converter.
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