phase converter questions

On 30 Aug 2004 22:31:35 -0700, snipped-for-privacy@krl.org (Dan Caster) vaguely proposed a theory ......and in reply I say!:
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Hehe! You can't "disagree" with somebody who has no idea what they are talking about! <GG>
Sorry. That was the impression I had. I kept hearing that RPCs were great...BUT:
    - the emphasis was on capital outlay. My limit is power available.     - there was frequent qualification of claims about capacitors and tweaking and people who had wonderful success with a given load. Very little about this vs a nice expensive "sedate" 3PH generator setup, or true 3PH power.     - SORRY. There was one about getting 3PH power on. At this stage, short of some sort of "community action" group, that's out of the question.         - I am one of those wacko individualistic socialists....BUM! <G>    
It started to sound like those betting systems. There are a couple that work, but the bookies ban you real quick! <G>
OK. As promised I did some searching. One (vendor's) claim was that an RPC properly built to match _itself_ (as in set up to fit the idler) was 95% efficient at best, falling to 85-90% at worst (no load or full load).
That is above what I would ever _dream_ of, for a motor driving an alternator.
I got the definite impression that even under varying loads, the efficiency was very high. You, Dan, are correct.
So now I have apocryphal statements that these things are great, and "actual" figures from people trying to sell them to me <GG>. Bugger!
However, I have to admit that if the claims for a well-tuned RPC are 50% out, the efficiency is still above a belt-driven motor-gen setup.
I have to admit that some of my caution here is "free lunch" stuff.....sounds too good etc.

***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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I really think you ought to put one together and see if it works for you. Since your limit is power available, let me tell you of one I put together. It was for a fishing rod blank company that had a centerless sander. This was about twenty five years ago so I may remember somethings incorrectly. But I think the main motor on the sander was a 5 hp three phase motor. I used a 7.5 hp three phase motor and a two hp single phase motor with a belt drive between the two. I forget the size of the breaker, but it was just big enough after some fiddling. The pulleys were adjusted until the current drawn by the single phase motor was about 85 to 90 % of the name plate current. Some capacitors were connected between one of the hot legs to the leg not connected to facility power. As I remember the current drawn by the single phase motor decreased as caps were added and then started to go back up. So some caps were removed so current was a minimum. Then some caps were added across the power line for power factor correction. I never try to completely correct for power factor. If you plot current as you add pf caps, you will see the first one drops the current a good deal, the second one drops it less. The third one even less. And remember that power factor correction only decreases the imaginary current. The real current varies with the load. The imaginary current does not vary with load. But for your case where you are current limited, reducing the current when unloaded, will cut the heating of the breaker and wires when you are not loading the output. And helps keep the breaker from blowing. Anyway I played around with caps of a couple of hours, and the guy used it for over twenty years ( But only used the sander maybe every ten days, it was not 8 hours a day 5 days a week ).
One thing to remember about RPC is that they are only generating the current and voltage for the third leg. So if you can get two thirds of the power out of a three phase motor running it on single phase power, you only need to generate one third of what a three phase generator would have to generate.
Dan

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On 31 Aug 2004 19:03:48 -0700, snipped-for-privacy@krl.org (Dan Caster) vaguely proposed a theory ......and in reply I say!:
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Yes. I suppose I absorb the time, build a small one, and see what happens.
I would have to go larger for welding, though.
As I said, I saw some figures that showed that these things are not nearly as twitchy as I thought, from what I had read. They also said that welders (including GMAW etc) are fine. Electronic gear needs more care. But then I would not run a lot of electronic gear on most alternators that I could afford!
They actually seem to be far more efrficient than motor-alternators. I did not realise this as I thought it was all about money up front (which policy I applaud, but in this case could not entirely live by<G>)

OK. Interesting. ***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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(Dan Caster) vaguely

If you weren't so far away - you're in WA, right? - I'd give you a 3HP 3 phase motor to play with. I got quite a few over the years but I'm on the east coast. Nearly every tool I have is 3 phase.
Frankly I think all this to-ing and fro-ing about faking 3 phase is fine & undoubtedly necessary for people living in the USA - their 110V power sucks and their tariff rates do too. Here in Australia - just go get 3 phase power put on and stop screwing about. I've had it put on to 3 separate places over the last 30 years without any dramas, just varying costs :-) I've got 3 phase 415V 90A per phase coming into my place and I can plug reverse a 7.5HP motor with only a momentary blink on the light circuit. It also means that I really, really don't need to worry about what size welder I want to run.
Paying the power bill hasn't been an issue - so far.
PDW
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Hey Peter,
I checked within the last year, and here it was going to cost $8500 Cdn (approx 6500US or 9300AUD). And that was for the utility company's work only. I'd still have to run in from the "pole", and change the service entrance at my house, and my panels. And it would have been 3 phase at 600 volts, so I'd need a transformer(s) to get 440-308-220-208 three phase, and 110-220 single phase.
So I have a bag of capacitors and an idler now. It works fine for the lathe and mill, but it dropped out something on the CNC which I have not taken time to troubleshoot yet, and I have not tried the surface grinder yet either, but at least I'm sort of "back in business".
Take care.
Brian Lawson, Bothwell, Ontario, Canada. XXXXXXXXXXXXXXXXXXXXXXXX On 29 Aug 2004 16:44:25 -0700, peter_d snipped-for-privacy@hotmail.com (Peter Wiley) wrote:

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On 29 Aug 2004 16:44:25 -0700, peter_d snipped-for-privacy@hotmail.com (Peter Wiley) vaguely proposed a theory ......and in reply I say!:
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Umm....I am 3 Km from the nearest 3PH. :-< It cost $8000 to get 1Ph put in just from next door.

***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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Well, Nick, the incremental cost for 3 phase should have been:
heavier poles, maybe. I had to go from 100mm round 6.5m steel poles to 125mm SHS 8m poles. If you had heavy timber poles, no difference.
2 extra wire runs. I had bundled aerial cable run in. To get the equivalent single phase supply - say 270A 240V - I shudder to think what the cable alone would have cost.
a 3 phase transformer instead of single phase.
Been there, done that here in Tas in the last year. It cost me $8K. Yes, you can buy a lotta single phase and 3 phase motors for the price difference, but all the screwing about in the world still won't deliver you true 3 phase, nor will you ever be able to pull more than (say) 90A off your single phase supply. Nor can you extend your power cabling anywhere near as simply & cheaply. I had the meter box put on the last pole and ran my consumer mains myself to my house, shed and to a future shed site by a dam. The cabling costs to run 20A 3 phase over any distance are a lot less than trying to run 60A single phase over the same distance, and I get to run 3 phase motors for water pumps etc. I ran a 63A 3 phase supply to a sub board in the house then pulled my single phase circuits off it. Ditto for shed and 20A down to the dam.
It cost me upfront but life is a lot simpler long term - which was my point. You could just leave that 6 HP motor on the sawmill instead of screwing about using the tractor PTO for example, coz you're gonna find you need to use the tractor to move stuff at the same time as you need its PTO drive, I'll bet. Been there - I have a 36" dia circular sawmill modelled loosely after Rick Buxton's. I designed it for a PTO drive so I could move it about on my NSW farm. In the end it was easier to move logs to the saw using the tractor. Course, if you have 2 tractors.......
PDW

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says...

Sounds nice - but I notice you did not mention anything about the peak demand meter.
Jim
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Peter Wiley

That's because here, there is no such thing. I pay for the kW-hours I use and at normal domestic tariff. Period. In fact I also have a 240V off peak metered supply that I can use for water heating and other approved activities. Funnily enough my water heater is installed with a 20A plug rather than being hard wired.
Precisely what I mean about you guys being screwed over on your power systems. First you have 110V meaning you need much heavier cable to get any decent amount of current and second your suppliers screw you over on the tariffs. We have neither problem so faking 3 phase is generally a waste of effort.
PDW
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says...

Ah haaa. Here one begins to understand why there's such a proliferation of home-brew approaches to generating three phase power in the US - a peak demand meter is invariably installed with polyphase service around here, with the idea that the user is commercial by definition if they run three phase machinery. The cost can be staggering.

Well, the utilities are pretty consistent in their treatment - we all get stuffed equally, alike - for the most part.
Jim
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On 30 Aug 2004 17:34:12 -0700, peter_d snipped-for-privacy@hotmail.com (Peter Wiley) vaguely proposed a theory ......and in reply I say!:
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Your power people must operate differently from my power people.
However, remember this is 3KM. I have to pay for _all_ of that mains 3PH. The laws are changing all the time, so I do not know whether I start getting dribbles back as others join up.
I knew one guy who wanted 3PH over a couple of Km and it was going to be $30,000.
I went through a huge battle some time ago about access rights when somebody was extending the power grid, and do not want that again. So I tried to get the 33KV line _taken off_ our property, back to the front gate. $8000......to _remove_ the power lines! I was told that:     - the transformer was useless, and that I would need a new one.     - The poles were useless.     - The earth would have to be done differently, because the one I had was usel...err upgraded.
Basically they were going to throw away all the stuff, the cabling was worth crap, and I had to buy all new gear on their behalf.
I admit they probably did not want the the job, and had an active reason to leave their gear there. But they had all the facts on their side. I could probably do a ministerial, stick my head up, and be PE #1 as far as the power authority is concerned from then on....not a good way to be in the backblocks...eh what? ;-<
To give you an idea, they wrote me a quote for that work. The qupte lasted 6 months. About 8-9 months later I made myself known to them about something that I was mildly not happy with. Within a week, I had a very firm letter from them telling me that the previous quote was null and void, (two to three months late). It _may_ simply have been a diligent clerk opening my file and fixing up outstandings....
But all else aside, AFAICS the power people _use_ people who want what I want to justify upgrading their tatty power system up to the latest, I am afraid.

Over what distance?

Again, your licensing may vary. If I do that it's illegal. Building a rotary converter is illegal. Building an _amplifier_ that is mains powered is illegal. It all depends on what's most obvious.

I realise all that. But see above.

Not at $30,000, it's not.

I do. I have been here 15 years and have been through all those decisions with chippers, saws, tractors, trailers, tippers, loaders etc etc. I admit I have thought about whether to take the saw or bring the wood. I constantly fight between sawing theo wood onsite, and then bringing back the pieces, vs dragging,/ carrying ghe (much harder to handle) logs and processing at a site. However, at present, I knw 3PH feed is out of the question, for all of its (enviously admitted, bugger it.) advantages.
***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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<SNIP> Greetings Nick, In your post you mentioned that building a rotary phase converter is illegal. Does this mean you can buy one and hook it up? Or is that illegal too. If so, why? And, could they tell? Would they need a search warrant? Sheesh, Eric
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vaguely proposed a theory ......and in reply I say!:
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Haha! _Building_ one is actually probably not illegal. I mis-worded! <G>
But no, I could not hook it up, unless it had a plug to plug in, and a socket to take out. I cannot wire it in.
I realise it _may_ be hard to tell who did what, if it's a bought one. But a home-built one one would be a little easier to spot, even if well done. If anyone in control was suspicious, they could ask me to prove installation by a electrician.
Interesting about the search warrant. Firstly, if I had any work done by an electrician, he has to submit a "ticket" to say it's done. It can be inspected. He may also report what he sees, of course.
A story. A little while back, I was in a situation where my bush-pig neighbour was stealing water from my dam (he set fire to the place while he was doing it), and repeatedly dumping his household rubbish on my property. I reported this to the police, who took no action, and the Council, who sent the Health inspector out, accompanied by police. He had more powers of entry and search than the police. They were there to provide muscle, and to arrest the guy if he tried to stop the inspector. So he and other statutory folk often have more power than police! ***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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wrote:

So, if it can be plugged in, why not plug it in? I am probably missing something here but it seems to be the obvious solution. In my shop some of the machines are plugged in. The largest plugged in machine is only 5 HP but the outlets and plugs I'm using have the capacity to be used with my 10 HP 230 volt machines. Eric
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vaguely proposed a theory ......and in reply I say!:
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There seems to be a misunderstanding here, to the point of discomfort. I am not deliberately being illogical. I actually regularly break this law, but some things get under the radar, others do not.
Building an RPC is painting a target on my arse.
The law says:
    - If I buy one, and it can be plugged in, I can plug it in.         * Buying one is an expensive option. I have seen them here (Oz) for $2000 or so for any reasonable size. I _have_ to buy motor and all, as otherwise, if I add my own motor, and any wiring, I am building it....
    - If I build one and wire OR _plug_ it in, it's illegal.         * Not to build (as far as I know), but to plug in. I have a 12KVA 1PH generator sans motor sitting in my shop. Until I actually connect it, nobody can do anything except steal it (and welcome to try. It weighs a ton!<G>)     - If I get caught, I am in the shit, and will be under the scope thereafter.         * I could be caught by any inspection         * I am not allowed to do _any_ electrical wiring in a shop.             - Once I start adding illegal gear on the scale of an RPC, I am on a difficult path. I get tied in to having to do all future wiring illegally. A sparky comes and works and sees the gear etc. Once I place something as large and obvious as an RPC in a workshop, any sparky worth his spark will pick it up. He is probably duty bound to report it, and since it's money out of his pocket if stuff gets DIY'd, he will probably do so with great alacrity.     - If I sell this place or for any other reason someone else uses any equipment that I have installed illegally, and they either don't like it or are hurt by it, I am in the shit in the first place, and _really_ in the shit in the second place.
I use tractors without ROPS, PTO shafts without covers etc etc. But as I said, some stuff slips under the radar. For some reason electricity is a very hot topic. There is a powerful trade incentive there, for a start, and it has a very high horse from which to dictate terms in order to protect itself. The building trade here is much the same. Owner building is _very_ difficult to do here.
Before you scream "nanny state" read a few of the posts about boat building in the US. We don't have anything _like_ half the rules about that here. shrug.

***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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wrote: A lot to indicate that OZ. is run by the almighty shop steward. If this is the case, I feel for you, but from a great distance.
Gerry :-)} London, Canada
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(Peter Wiley)

Yeah but - you've got what, a single 33kV line coming to a 33kV-240V transformer now? On poles? Running the extra 2 phases isn't that big a deal.

Been there done that, cost $12K back in 1984 for the same sort of distance. The property cost $40K at the time.

Ah, the clause in the supply agreement giving the power company unfettered right to run a ROW anywhere they like to connect neighbours to the supply as a condition of giving you (or a previous owner) supply? Sorry, got little sympathy for you if so. Choice over where the ROW goes is a different matter but there are so many people with the 'stuff you Jack, I'm OK' attitude in the country these days that running power becomes even more prohibitively expensive. If you have a serious problem with allowing power ROW you can always cancel supply altogether, go solar/wind and have them remove the gear. This might not void their ability to use a ROW tho. Also the $30K for 3 phase may seem cheap when compared to solar/wind/diesel etc even for 240V 90A supply ....
So

Heh. I have a 110kV line across the front of my NSW place. They'll relocate it when hell freezes over I reckon. Then Telstra laid fibre-optic along the powerline ROW and there was nothing I could do about it either. Too bad I'd put a big dam right in the middle of the ROW under the powerlines some 10 years previously. Shrug. I knew the conditions when I bought the place.
Part of the social cost of *you* getting on the power grid is being a good citizen so others can get on the grid. I suspect from the above that you wanted the 33kV line moved back to the other side of your boundary just because someone else wanted the line extended to their place through your place. Somewhere or other, up the line, it probably crosses someone else's private land. Where would you be if they did the same thing?

Sounds familiar. However they're responsible for installed plant so you can see their reasoning. You ask for their opinion on their gear in writing then ask the area manager why it was so bad, nothing had been done? No?

They're public servants FCS. If you give them a hard time and go over their heads about unjustifiable policy, they're *not* going to victimise you, they're gonna see you as a person who causes them grief. If you then send a nice letter in to their bosses when they do something you want done, they'll get the message. You'll get service. This has worked for me over the last 30 years, along with starting off with a good attitude up front.

Wouldn't have mattered anyway so what's the point? If the orig letter said valid for 6 months, the 2nd one was redundant.

Yeah - depends on who wants what how badly. Friend has similar stories about his place in NSW. To add insult to injury, he can buy the same size transformer meeting all specs for half the price but he's not allowed to buy/install it. He's also a licensed electrician.

This one was only 300m. The big cost was the transformer tho, about $6K IIRC, not the line work. Irrelevant where the xformer is distance-wise to its cost.

Why? I had a licensed electrician check, sign & certify all work. That's all you need for anything past the electricity meter as long as you do it to code. I have a number of contractors pretty well permanently working for my group so getting stuff done isn't a problem I'd admit, but it's never been an issue on my NSW place either.
Here in Tas Aurora Energy (ex HEC) is pretty good. Their linesmen are cooperative, their staff are helpful and I have zero problems with them. I had the same experience dealing with people in NSW.
Building a

Hunt up a big VFD and use that. I got given a 4kW one. It's 3 phase in/out tho.

If you're running a farm, business etc I'd argue that it still is.

I've been thru it with the logs too. Depends if you're sawing lumber or firewood maybe. For lumber you still need to lift the log to the saw carriage & feed it thru the blade regardless of where the mill is and IMO it's easier to set up the lifting gear next to the carriage once than move it all, re-level it etc etc. A local here has a Lucas mill and for building size lumber this is a lot faster than I can haul/cut timber with my circular mill rig. In fact I buy my std size 100x50, 150x50 etc off him these days.
Had my NSW place 20 years then decided to relocate to a civilised climate next to the water and play boats. Now I'm doing it all over again :-( 6 cubic metres of machine tool accessories, the small lathe and small mill just arrived. Another 10 cubic metres of machine tools still to come as that stuff is hard to replace here. I think the tractors & sawmill etc will stay on the NSW place until I decide what I'm going to do with it. 3 places is one too many.
Anyway, if you see yourself as stuck with single phase only then you are. The rotary converters don't look all that hard to do & they obviously work. As I said I'd prefer a single phase in 3 phase out VFD but I'm used to having them about the place on ships etc.
PDW
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On 31 Aug 2004 20:58:06 -0700, peter_d snipped-for-privacy@hotmail.com (Peter Wiley) vaguely proposed a theory ......and in reply I say!:
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I penned several replies to this, dealing with each statement you made. In the end I gave up.
Just this in the end. I will have to live with your judgments of me as a country citizen. You seem to have the wrong end of the stick about my situation from the comments you have mde. ***************************************************** I have decided that I should not be offended by anybody's behaviour but my own......the theory's good, anyway.
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vaguely proposed a theory ......and in reply I say!:
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Ahah! OK. So simply throw grunt at the thing and avoid the fiddly bits? That was something I had seen, but not understood (absorbed into my soggy brain) the reason for, I think <G>
I agree about the lack of cheap/free 3PH alternators in the lower ranges. They usually have a motor (fuel) attached. I did have the opportunity yo buy one reasonably cheap. Did it work???? shrug. I never went there, because I was not sure if my idea was the right way to go.

snip
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vaguely proposed a theory ......and in reply I say!:
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I did some reading. I remember now what my reservation was. While you can throw plenty into the RPC, they are not good at allowing the driven motor to produce full power. I am wondering what happens to welders etc. Welding is one area where I see real bargains for very powerful MIGs etc. I have seen a MIG that gets 350A from 240 volt, but it was a new model, brand new with a VERy "new" price!

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