RPC to XMFR question

So I'm probably buying a used Fadal mill. It is currently wired for 480 volts. The shop it is in uses an inverter to convert the incoming
240 single phase to 3 phase which is then sent to a step up xmfr and then to the mill. The RPC maker is no longer in business so I can't ask them if the RPC I have can be connected to the xmfr. Can this be done? I think I can re-configure the mill to run on 240 volts but I'm not sure. Furthermore, there are already wires in my shop that can supply power to the Fadal but I think the gauge might be too small for the amperage draw if the Fadal is wired for 240. Adding wire would be kind of a pain as I would need to pull wire through about 40 feet of conduit. I can do it but it's a pain plus I would need to buy 180 feet of wire because the machine is 3 phase and there is another 15 feet of wireway the wire needs to go in. The wireway is the kind where you just remove the covers and lay the wire in. The conduit goes from the wireway up the wall 18 feet up, across the building, and then down the wall to the wireway on the opposite wall. Thanks, Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Every Fadal I've ever seen except for thew single-phase models has a built-in multi-tap transformer inside of the rear cabinet which allows connection to any mains voltage between 190 and 510 volts.
That said, unless your phase/phase voltages are all within 5% or so of each other, you may need to rotate your phases so that the 100v AC bus isn't low because this may cause problems with relay chatter, sluggish carousel rotation and so forth.
Other thing is IF it has rigid tapping, and your wild leg is more than 5% above /below the others, then there is parameter setting you need to take a look at and correct if necessary...otherwise it will affect the spindle accel /decel time constant possibly causing breakage of small diameter taps and overly loose fits on the larger ones.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sounds like PM is pretty sure you can change your Fadal. That's the better way to go.
You can also use a three phase transformer to step up to 480. I do it for my plasma cutter. I had to play with the taps the get the voltages right.
Karl
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I step up here also, with a 30kva dry type delta/delta and also with an old 400amp welding transformer that Iv'e reconfigured to operate as a wye autotransformer..
But depending on exact winding configuration and conection, issues can arise with isolation, detection of load-side ground fault detection at the supply side, loss of one phase, so forth and so on...
As such, it's probably the topic for a different discussion.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I guess I should add that I have 3 fadals here, two are 3ph I run both of those pretty much all day 5 days a week off of an RPC and only rarely is there a problem.
In any event, you want to make absolutely sure that in the event of a momentary power outage, your rotary unit will shut down and that it will NOT try and restart by itself
--otherwise, you are risking serious damage to the equipment...and even so, you will still want keep set of spare mains fuses and a backup surge supressor card and / or some 250vac rated varisters on hand.
The proper fuses are class RK1, ( fast acting ) and if you replace them with a different variety or if you permanently remove your surge supressor card then you are a blithering idiot.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 10:14:09 -0700, "PrecisionmachinisT"

Greetings Karl and PM, Thanks both for your speedy replies. After reading your posts and the installation manual it looks like I may need to run the XMFR. Even though the machine can be adjusted to run on 240 volts I think the surge suppressor board in the machine is the one for over 240 volts. If that's the case then maybe I need to supply the higher voltage. Since the machine comes with the xmfr it's up to me whether to wire it in. The manual says to use 10 gauge wire if running at 480 volts less than 100 feet. And I'm really happy to see that Fadals are being run of an RPC. My RPC has been trouble free for 12 years or so and runs two machines with Fanuc controls. And it will not re-start after a power outage. Which is good since here on Whidbey Island we get several power outages or brownouts every time it gets windy. Cheers, Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well I'd probably just change the surge supressor to 250 volts and sell the transformer on Craigslist but I guess that's just me.
Just curious...what is the model and serial number ( year ) on your Fadal--I can probably provide a lot of help /information...
Oh and here's a "heads up" for you--(if it's a box way machine) the first thing to do is put an indicator in the spindle, touch the table with it and set a zero, then you move the table all the way left, all the way right and all the way in and out...any rise /fall seen in this test means that the turcite is worn out and you probably want to look at buying a different machine.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 11:45:21 -0700, "PrecisionmachinisT"

The machine is a linear way machine. It's in a shop where I've been working mostly for the last year or so. So I know the recent history of the machine and how well it runs. The shop owner is closing the shop which is why the machine is even up for sale. The model # is 914-15, the date is 1996, serial # 9603340. So, since I can feed the xmfr with the RPC I'll do that for now because it is working that way now and the machine comes with the xmfr. Then down the road get the 250 volt suppressor, pull wire if need be, and sell the xmfr to cover the cost of the change. Thanks for the offer of help. Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's probably a good thing, more than likely it has no central lube system and uses grease instead--make sure and use the proper grease and give it a squirt or two every couple weeks whether you've been running it or not...this is definately a case where a little bit fairly often is much better than a whole lot every once in a while.

Then it's a vmc-15, and was made in same year as my smallest Fadal which is happens to be serial #9603180
In all likelyhood you will have the 1400-4 cpu--I STRONGLY suggest don't upgrade to the -5 cpu athough if the module 1610-xx exec card that's attached onto the 1400-xx card is any earlier than ver94.1 p4-3, (which was the final revision available for the -4 cpu ) then you probably should get the program update, if you have problem sourcing one let me know I have several extras you can have

Hey whatever works...
--and if it turns out your phase converter isn't quite big enough to cover all of your machines at the same time well you'll probably know it before too long and most likely no actual harm will be done.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 13:47:13 -0700, "PrecisionmachinisT"

It will start 15hp and run 60. And it will start the CNC lathe with a 10hp DC spindle drive and the CNC mill with a 5hp induction motor spindle at the same time. But that hardly ever happens. The new to me lathe has a 15 hp spindle so I'll need to be careful when its spindle is programmed flat out so that it won't start the spindle when something else is trying to start. If it becomes a problem then it means I'm busy enough to afford buying a solid state three phase solution. Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 15:46:26 +0000 (UTC), snipped-for-privacy@whidbey.com wrote:

Yes, you can hook a 3-phase step-up transformer to the output of the RPC, but you get the loss of the transformer in the circuit. See below.

You have to repull the wires if they will be operating at 240V.
Even if you put the Rotary Converter and the step-up transformer right at the power panel and send 480V down those wires that are now miraculously large enough, you _still_ have to run new wire - you need to add a third hot leg to send the 3-phase to the machine.
Either way, it has to be done.

Watts Is Watts - when you double the voltage you cut the amperage in half and can use smaller wires, but the Watts remain the same.
If you run the RPC and Step-up transformer the Mill draws the same watts either way. But you have the losses from running the transformer too,you lose some power in the conversion, you put in 110% to get 100% out.
And it wastes a significant number of watts energizing the transformer even when it sits idle - feel it, it's warm...
Pulling new wire to beef up the 240V power at the machine location is by far cheaper than any other solution.
Adding a proper 240V 3-Ph or 480V 3-Ph service is not cheap and darned near impossible in a residential area. And if you don't have all three phases of the 4KV or 15KV or 35KV distribution power already at your pole, and they have to extend the third leg a few miles to get it to your location that could easily hit six figures.
The mill most likely has dual-wound motors, that's the standard. If it does, you're not too far away from making chips. Install the bigger breaker and the bigger wire, install the RPC next to the machine, wire the 240V 3-Ph straight to the machine, and go.
--<< Bruce >>--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 12:10:33 -0700, "Bruce L. Bergman (munged human

Greetings Bruce, I already have # 8 or # 6 wires in the conduit for a machine that's leaving. I just don't remember what gauge and it's probably the lighter gauge. If I have the heavier gauge then that's great and I may be able to get rid of the xmfr. If not then I'll connect the machine with the xmfr and when I have some time and some help and some more money pull some new wire and get rid of the xmfr. Thanks, Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 19:38:46 +0000 (UTC), snipped-for-privacy@whidbey.com wrote:

Before you start all the work on the install at 240V 1-Ph and the RPC and step-up transformer and all the associated garbage...
Call the Utility wonks on your island and ask them what the hoops are to get a second transformer set and run an Open Delta 3-phase 240V line - they do that a LOT for smaller loads like well pumps and elevator machines. If you don't ask, you'll never know.
Better, they place two more small transformers so you can have Delta 240V. Best, a separate rack of transformers for 277/480V Wye or 480V Delta 3-Ph service - and if you mess up Real Bad you won't knock out your lights too.
You might get lucky and they won't charge a ton for the service transformer rack and the hookup. Helps if you let them know where to go and get a custom part machined up in a hurry, too.
If they'll hook you up for a reasonable fee, you can always get a slightly used 240V or 480V "Instant Service Switchboard" from a used equipment broker and you can be up with Real 3-Phase fairly quickly, and for not all that much.
And like PM said, changing out the surge arrestor boards is cheap if that's all you need to run it native at 240V. Keep It Simple, Son!
--<< Bruce >>--
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 31 Oct 2011 23:19:22 -0700, "Bruce L. Bergman (munged human

Greetings Bruce, The nearest 3 phase is a little over 1000 feet from my shop. Back in 1997 I was quoted $15,000 just for the wire. Then $1800 per pole because the poles carring 3 phase have to be taller than the ones carrying single phase. I guess that was their way of saying no. They did however push under the road from the pole across from my place for what amounted to no charge. So I have 600 amps available. Thanks for the advice though. It never hurts to ask in these tyoes of situations. Since I already have a shop all powered up it's no hassle now dealing with the RPC because it's been running for years. Eric
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.