Three Phase Converter Question

[GaryBDavis]

I need to get a 3-phase converter for a 16" metal chop saw. The only experience I have with phase converters is the static type I have on my mill.

I know there are static and rotary converters, but don't know for sure which one I should get.

The chop saw has a 5HP motor that runs at 1720RPM. I've heard that static converts aren't good for "freewheeling" loads, high starting current and frequent starts. I'm not sure if the chop saw would fall into that category or not.

If you guys know of a good on-line source to buy them from and what brand to get/stay away from, please let me know.

Thanks.

 

[ZJ_HR]

You can use variable speed drive for that purpose. It will vary frequency from 0 to desired freq, and will run your saw as you want. Just two questions:
-network voltage (single phase)
-saw motor nominal voltage (phase to phase)
These values need to be similar for VSD, as it is not a transformer.
-saw motor nominal current

I'm familiar with Telemecanique (Europe) or SQUARE D (America) speed drives.

 

[RedRocker]

I run my Mill on a three phase motor that I rope start. Cheap and easy way to do it. A three phase will run on single phase power, it just won't start. All you have to do is get it spinning and shoot the juice to it, it will generate a third leg for your other machine.

 

[SPIKER]

Hey:

A rotary converter is basically a 3 phase motor which has a speed switch and some inductors or caps in the line side which slows the phase shift for a few seconds once it gets up to speed they are usual;ly switched out. to run the 5 hp grinder you will need a 7.5 hp converter or better yet a 10hp unit. there is a good amount of power loss when running it this way. they are also not cheap... they can be built by home users with kits and provide you're own 3hase motor then. often for a 1 or 2 units it is better to but a freq drive as mentioned above they can be had for a few hundred bucks NEW and e-bay stuff even cheaper. you have to watch the input voltage and phase requirements, in you're case 240 single phase input and then output of 240 volts-3phase.

at one time I had some links to parts, one place is http://www.surpluscenter.com
(I think I typed that right?) that you could buy or build the rotary setups.

MarkM

 

[AntrimMan]

I have walked away from some opportunities cause they had 3 phase motors and IMHO they wern't worth the cash for a converter or new single phase motor. Would have been nice to have but too beat for the needed investment.
Do you have any way of posting a schematic of this motor approach you mention? How is the phase supply motor sized vs the tool motor? I have 220V single phase in the garage, how would the other phases affect the rest of the supply?

Thanks,
Martin

 

[Farwell]

There is a guy on Ebay that has all of the information on the phase conversion and he sells it for a few bucks. It is cheaper if you download it. The information is very clear and easy to understand with all of the information you would need.
Farwell

 

[DougM]

Would it be possible to run a older 3 phase welder with a converter ????

and if so how large would one need ??

DougM

 

[Charlie_in_TX]

I believe most 3 phase welders can be run single phase. It will have a little more DC ripple and it will need to be derated to 2/3s nameplate (you would be using 2 sets of diodes instead of 3). So if it was rated for 400 amps you would derate to 270 amps.

 

[Farwell]

I do not know much about 3 phase equipment. I have been reading up on 3 phase thinking that at some point I will be buying a Bridgeport mill. A lot of metal working equipment is wired for 3 phase and can be bought at a lower price because a lot of hobby machinists are afraid of 3 phase. I never thought about a 3 phase welder set up. I will have to keep an eye on this thread to see if your question is answered.
Farwell

 

[Larstan]

The answer is yes you can run a 3 phase welder on a converter. The problem is that a welder is actually putting out a lot of amperage, not just turning a spindle to do some work. I have a 300 amp hobart tig 3 phase welder, transformer type. I have done extensive research on making this thing work on single phase. I talked to a rep at Temco and he told me that to run the welder at 200 amps the converter would cost around 5K thats $5000.00. You have to almost double the capacity of the converter for the output that you want and welders are a completely different animal than a motor. Here is a link to a conversion chart Temco phase conversion It might be cost effective on a really small welder or if you have a business and moved to a new area with no 3 phase but for even a medium sized welder to get full use you would spend more than the cost of a brand new single phase welder.