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VFD , Rotary or Digital phase converter for my machines?

Spud

Diamond
Joined
Jan 12, 2006
Location
Brookfield, Wisconsin
I have been brooding over this for months.

I would like a Phase Perfect in the 20 or 30 hp range but can't spring the dough.So here is my options, Rotary Phase converter or VFD or Digital Phase converter (not PP).

American Rotary has a 30 HP rotary phase converter for $1795. Same converter is listed as suitable for CNC app also.
http://www.americanrotary.com/rotary-phase-converters.html

I don't have any CNC machines now but was thinking of getting a small CNC lathe (older Hitachi or Mori or Mazak) and starting a small garage operation making parts (possible future plan). Also thinking about mechanical screw machines.

At the moment, the most powerfull machine I got is a Monarch Series 71 , either 15 or 20 Hp. I got a Schaublin 102N and a small Hardinge Mill that I need to sell in the near future. Even though I am sure they work, I can't claim as such unless I check just before sale. Don't know HP rating on those but can't be more than 10hp. Got 2 drill presses also which should easily be under 10 hp. If I have a 20 hp machine, do I need a 25 or 30 hp converter? I am also gona need transformers, after or before the converter or VFD?

I plan on get a sliding table saw in the future. I won't run more than 1 machine at a time so is it feasible to plug and unplug machines to stay under a phase converter's max HP rating ? I assume this isn't done with VFDs, that they (VFDs) are attached to each machine?



Now about non Phase Perfect digital converters .What brands are commonly used, reputable?

Anyone know about these 10 HP Digital inverters from Drives Direct of Uk?
http://cgi.ebay.co.uk/10-HP-3-PHASE...yZ112399QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Upto 30 hp Digital inverter , single phase 240V in and 3 phase 415V out.
http://www.drivesdirect.co.uk/Products/Digital_Inverters240_415.htm

Or how about this Teco 7.5hp digital converter
http://cgi.ebay.co.uk/7-HP-DIGITAL-...ryZ42938QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Drives Direct of Nottingham UK.
http://www.drivesdirect.co.uk/
 
If you are selling the schaublin and the hardinge, you don't need a super big
converter to test those machines. They're both one hp or smaller. A single
3hp three phase motor, set up as a stone-age converter, will run either of those
fine.

Also you could purchase a very inexpensive VFD to test either of those small machines.

Jim
 
Jim

What is a good VFD for the Hardinge and Schaublin?

Is it a simple plug-n-play to connect the machines to the VFD? I got 4 machines I need to run (not including the Monarch)
 
Those links you posted are simply inverters.

You're familiar with the sine wave of AC, of course. An inverter creates a blocky signal instead of a nice fluid sine. In one of those auctions, the seller talks about a sine wave filter that is available as an add-on. This is probably some system of capacitors used to take the edge off the signal, but it won't be anything like the power you'd get from a phase perfect.

Phase Perfect is the absolute best thing you can get for your shop. If I were you I'd try to nab a used unit from someone who got three phase installed.

You're going to need a VFD for each motor you want to control. Basically you buy an oversized VFD and switch it or trick it to take single phase input. Mitsubishi VFD's are rated and configurable for single phase input. There are many good ones.

With all the different three phase loads you're likely to have in a shop, I'd recommend finding a cheap RPC in the 5-10 hp range to power your general three phase stuff, and a VFD if you want to be able to fine tune your RPM's on any single machine.

Well now hold on, that Drives Direct company has actual digital phase converters. They output a true sine wave and are probably built with IGBT architecture similar to the phase perfect. This warrants further investigation.
 
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Build a pony-start RPC.

If I were in your situation, I'd build a pony-motor-started RPC from surplus and junk... it's a cheap-and-fast way to get a fair amount of 3phase going.

Your Monarch may have that big'a motor, but don't expect to actually NEED that much power unless you really plan on hogging metal. If you use the machine only for finishing and low-power cuts, you could probably get away with much less.

As for the other tools, you can run them off the same RPC (all at the same time, even), and look for VFDs as time and funds permit... convert them one-at-a-time as need requires.

While you COULD mangle up some way to move the VFD from one machine to another, they really DON'T like that, and it'll be quite a headache. Fit one direct to each machine... that's what the VFD is expecting... it wants to be wired directly to the motor leads.
 
DaveKamp

I am not considering the home brew converter route because I don't know much about electrical matters. Even if I do spend the time reading the ins and outs of building a converter, I wouldn't be confident implementing it, will keep doubting whether its safe.

I am looking for a ready made solution.

From the replies, it seems like a phase converter is what I need unless I plan on outfitting every machine with a VFD (too expensive a proposition).

So would most agree I am down to a rotary converter or possibly something like the Digital converter from Drives Direct?

I don't know who is selling a used PP, but I assume price will be close to a news one.
 
Digital Phase Converter = "They have a digitally stabilised sine wave three phase output with an optional NEUTRAL output that is suitable for powering almost any machine in its power range"

IOW, a simple VFD with some bells and whistles.

The Phase Perfect is a digital device, too, but it passes-through the A and C phases (equivalent to the single-phase L1 and L2, BTW), as-is, while it internally generates a high voltage phase which is digitally controlled so that when it is added to, or subtracted from, L1 and L2, a true B phase is generated.

I am assuming these so-called Digital Phase Converters are actually fixed-frequency VFDs, with all three phases being digitally generated, in order to skirt Phase Perfect's considerable patents on phase conversion.

The Phase Perfect is just like utility three-phase, in that it can absorb considerable power, as in those two out of four quadrants in which an SCR-type drive is regenerating power in order to effect braking.

Can the so-called Digital Phase Converters do that, too? So far they aren't saying, but my educated guess is no-way-Jose.
 








 
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