Author Topic: starting from scratch in tennessee, offgrid machine shop.  (Read 31857 times)

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ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #27 on: January 10, 2013, 07:03:29 AM »
No, that's a 120/208.  You need a 120/240 high leg delta generator (based on the description of your stuff).  Some stuff that runs on 240 three phase can also be run on 208.  You'd have to look at the tags on your stuff.
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mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #28 on: January 10, 2013, 08:15:35 PM »
alright, this made me expect to see 208 on the tag. 

Just make sure you get a big enough genset to run your split phase loads because you're only using the two 120 volt legs for split phase power, and the high leg (208V) is not used.

heres some high leg delta info ill leave here for anyone else looking down the road.
http://en.wikipedia.org/wiki/High_leg_delta
http://www.electriciantalk.com/f9/120-240-volt-3-phase-delta-high-leg-5166/

so how do i determine if a unit is high leg delta wound or not?  ive never seen delta or wye on a data plate before. 

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #29 on: January 10, 2013, 09:44:11 PM »
so how do i determine if a unit is high leg delta wound or not?  ive never seen delta or wye on a data plate before.

It's not going to say that on the data plate because the voltage of the system tells what the winding configuration is.  There are three types of three-phase power - three wire delta, four wire wye and 4 wire delta.

120/208 is a wye configured system (4 wire wye).  The neutral is hooked to the wye point and it's a symmetrical three-phase system where you get 1.732x leg to leg voltage that you get leg to neutral.  Three-wire delta is also a symmetrical three-phase system with no neutral.

Four wire delta (120/240) is not symmetrical.  You get 240V between any two legs but you get 120V from two legs to neutral and 1.732x (208V) from the high leg to neutral.  It was invented mainly for rural areas where three-phase power was needed but split phase (120/240 single phase) was also needed and could be supplied from the same service.

A 120/240 three-phase generator will say so on the data tag and internally it has a normal three phase delta connected winding with a center tap neutral on one phase.  It fell out of use because of changes in NEC and different class services being provided by one service.  However, it is still in common use in rural areas and farms that have three-phase power.  You're not going to find a 120/240 three phase generator all that easily in industrial applications because those are all 120/208 or 277/480.

So you have three options -
1.) Most stuff that is tagged for 240V three-phase will run on 208.  But it draws more amps, runs hotter and is less efficient.  You have 120V single phase power but your split phase power is 208 which will usually require a step up transformer to run 240V single phase motors because they will run very hot on 208V.

2.) Get a 277/480 generator.  Most stuff that runs on 240 delta three-phase will also run on 480 wye if you rewire the motors and transformers (like in welders) for wye configuration.  This makes your motors run a lot cooler and you can use a lot smaller wiring.  You can install single phase 277 volt lighting in your shop.  And you have to install a transformer for split phase 120/240 volt loads.  This is what we use here on our place.

3.) Start looking for agricultural standby generators instead of industrial.  240V three phase is most common for standby farm generators.  Tractor PTO driven 120/240V three phase generators are a dime a dozen and they all run at 1,800 rpm, regardless of whether or not the PTO speed is 540 or 1,000 rpm.  They have a gearbox on them.  Go to someplace that that handles tractor PTO generators (Winco or whatever) and you'll find all sorts of them.  Cheap.  Buy one, haul it home, pull the generator off it, couple that generator up to a 1,800 rpm engine, weld together a skid frame for it and you got yourself a generator.
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ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #30 on: January 10, 2013, 10:39:57 PM »
There is a fourth option that I forgot to mention.

If your loads are primarily single phase 120/240 you can buy a single phase 240V generator and install a rotary phase converter to generate three-phase power for your three-phase equipment with the single phase generator.

You can build your own rotary phase converter out of a big three-phase motor.  Three-phase motors will run fine on a homebuilt rotary phase converter.  But if you have three phase CNC equipment you will probably have to buy a commercially built rotary phase converter that has digital controls for perfect voltage balance on the three legs.  The commercially built converters usually have a built-in starter too.  With a homebuilt one you'll have to come up with a way to spin it up because it won't start by itself on single phase power.
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mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #31 on: January 11, 2013, 07:29:30 AM »
im really starting to feel like i owe you for all the time youve spent with my questions.  is there anything i can do for you chris? 


the PTO genny sounds best.  it would be pretty easy for me to come up with an automotive diesel to run this.. ford brazilians, old DT466s and NTC250s are cheap and plentiful.  plus Vbelts and lots of room for accessory drive off the front half. compressor head, vaccuum pump, AC, etc. 

thanks again, i know what im lookin for now.

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #32 on: January 11, 2013, 10:59:29 AM »
For the most part use 200% of the prime power kVA rating of the generator for engine flywheel hp, and 180% of the standby power kVA rating of the generator for standby hp.  So for a 100 kVA generator put 200 hp on it for prime power, 180 hp for standby.

And remember that DT466's and old NT220's etc, are not rated at 1,800 rpm.  So the engine derate at 1,800 has to be taken into account too.  If you want an engine that will run 50,000 hours with just about zero maintenance spend the extra buck on a 12-valve B-series 5.9 Cummins.  Again, go to an agricultural salvage yard and you can find them in everything from CaseIH tractors to 1640 combines and you can buy a brand new skid engine from any CaseIH dealer for pretty good price.  Don't buy a Dodge pickup engine without budgeting what it's going to cost to put a different injection pump on it that has the full-range governor.  All the ag engines have a full speed range governor in the pump, where in the automotive application they're only governed for max no-load speed.
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dnix71

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #33 on: January 11, 2013, 04:51:08 PM »
Even in big cities a three phase generator can pay for itself.

I used to pick/deliver a print shop route. One of my customers on Belvedere Road in West Palm Beach had a three phase gen in the loft of his warehouse bay to run his Hamada sheet fed press. 240 split phase 100 amp service was at the back of the shop. There was 3 phase 100 feet away across the street, but FPL wanted $20k to string wires to add the service to him. He paid the electric bill of the neighbors' bay in exchange for tapping his 100 amp panel. Even 200 amps at 240 was just barely enough to run things. He would have to turn off lights or the a/c when he was bumping the Hamada to set up a job.

But he made money with that Hamada printing 4 color brochures for people selling $million estates on the island of Palm Beach and did such nice work that he had no shortage of customers.

mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #34 on: January 12, 2013, 02:48:46 PM »
No, that's a 120/208.  You need a 120/240 high leg delta generator (based on the description of your stuff).  Some stuff that runs on 240 three phase can also be run on 208.  You'd have to look at the tags on your stuff.
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Chris

so i work at S&W, we have 52 acres of CNC equipment and electricians who deal with up to 13,800volts coming into the electrical vaults.   all they do is wire machines, and i polled all 6 of them.  all of them said to avoid a high leg delta and instead go with a 120/208 wye generator.  i explained my loads and each of them agreed that my 240 equipment would run on 208, just at a higher amperage.. not enough to warrant an increased wire guage in most cases, but perhaps a few sizes up on the overload heaters.   going with the high leg delta leaves me with 1/3 less space in the panel (because the high leg cant be used) and the possible unbalanced loading issue. 

please dont take this as me doubting or criticizing you chris, im just trying to cover all my bases.  i personally would feel warmer and fuzzier if all my stuff said 240 on the tag, but i dont know enough to choose a side, and im not sure what i have that you doubt will be happy on a 120/208 wye.  was there something specific about the needs i described that disqualifies a wye?  im also under the impression the wye has a neutral (that i will need to get 110vac single phase without the use of a transformer) and delta does not.

thanks again for your time!

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #35 on: January 12, 2013, 03:05:40 PM »
but i dont know enough to choose a side, and im not sure what i have that you doubt will be happy on a 120/208 wye.

Yeah, industrial guys would say that because they've never worked with a high leg delta system.  The problem will be 240V split phase stuff (welders, air compressor, water heaters, single phase lighting, etc.).  You will have 120V single phase from any leg of a 208V three-phase service to neutral.  But you will not have 240 split phase because the legs are 120° electrically separated.  So you'll need a 208 three-phase to 240V single phase buck transformer.
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mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #36 on: January 12, 2013, 05:15:10 PM »
thanks for the quick response.. ill let that soak into my head for a while.

mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #37 on: January 13, 2013, 09:53:22 AM »
im getting up to speed on the ins and outs of 'split phase' circuits and loads.  this article is really helping.

http://www.allaboutcircuits.com/vol_2/chpt_10/1.html

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #38 on: January 13, 2013, 10:19:58 AM »
There's a number of factual errors in that article.  I don't know who wrote it but he/she needs an education.

First of all, European power, as stated in the article, is 230V, not 240.

Split phase power is not two 120 volt supplies that are in phase, as stated in the article.  It is two 120 volt (in relation to neutral) legs that are 180 degrees out of phase.

If you intend to use split phase power at all (which is just about unavoidable in the US), either for your home backup from the shop gen, or in the shop itself, 120/240 high leg delta three-phase service is a better option because it eliminates having to use transformers.  We have 277/480V at our place because we have 100hp motors and a single motor draws 200 amps, and two of those 100 horse motors at full load make our little 250kW Cummins genset blow smoke to the sky.  But if your total amp draw to any load is under 100 amps you can use 120/240 three phase with no problems, and have 120/240 split phase without transformers.
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DamonHD

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #39 on: January 13, 2013, 01:46:50 PM »
Chris: European power nominally ranges from about 220V to 250V given a fudge to allow the (higher) UK range and (lower) continental voltages to be considered "the same" across the whole EU.

Plugging in a Kill-a-Watt-like meter to my nearest power socket right shows me 245.5V for example.

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ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #40 on: January 13, 2013, 02:16:07 PM »
Damon, that's because the power companies play with voltage and frequency just like they do here, depending on demand and time of day.

The European nominal is 230/400 50 Hz.  You guys had a transition period from 1995–2008 when countries that had previously used 220 V changed to a narrower asymmetric tolerance range of 230 V +6% −10% and those (like the UK) that had previously used 240 V changed to 230 V +10% −6%.

Our son-in-law works at a factory where he's Maintenance Supervisor.  On the night shift they were tripping breakers and overheating and burning up 208V three-phase motors one right after another.  Our son-in-law found out the Mains voltage was being dropped from 10:00 PM to 5:00 AM to 115/200 and 59 Hz.  He went around to several other places and checked and found the same thing.  He documented all of it.

Then he contacted the power company and confronted them with it.  They denied it and said go ahead and take us to court because you'll never prove it.  Almost like a miracle the Mains voltage and freq didn't drop anymore.

The power company was clocking their generators down at night to save money on fuel under low load demand times, which at the same time caused people's equipment to draw more kWh and the power company comes out smelling like a rose with higher shareholder profits.  Our son-in-law filed a formal complaint with the Public Service Commission and it got dismissed due to "circumstantial evidence".
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mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #41 on: January 13, 2013, 09:00:25 PM »
Quote
If we mark the two sources' common connection point (the neutral wire) with the same polarity mark (-), we must express their relative phase shifts as being 180o apart. Otherwise, we'd be denoting two voltage sources in direct opposition with each other, which would give 0 volts between the two “hot” conductors. Why am I taking the time to elaborate on polarity marks and phase angles? It will make more sense in the next section!


the second page is where it gets technical
http://www.allaboutcircuits.com/vol_2/chpt_10/2.html

dnix71

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #42 on: January 14, 2013, 10:50:23 AM »
I would be wary of running 240v equipment on 208v. We only have 3 phase 208 in the shop, but one of our engraving lasers is 240v split phase and the big laminator also is. Both pieces of equipment were installed by their makers and both said the lower voltage would be no problem, but they were both wrong. The laminator has heated rollers and the heater, wires and breakers burned out so many times they were forced to buy a buck transformer to correct it.

I watched the tech trying to calibrate the dual power supply on the 4kw laser and he couldn't. I reminded him that we didn't have the proper supply but he refused to acknowledge that as a problem and left the supply unbalanced. We blew power resistors on the boards every thing we started the tube, so we were forced to leave the laser powered up all the time instead of shutting it down at night. The 208v in the shop isn't even 208. While the tech was there I got a meter and read the voltage on the line under load and it was 190. A 208 appliance will run from 190 but a 240 appliance sure as h3ll won't.

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #43 on: January 14, 2013, 11:43:57 AM »
That's one of the problems with 208V three phase power.  You can take 208 single phase off it by using two legs, and it will run resistive loads at lower wattages with no problems.  But it won't run sensitive equipment or motors because the two legs are 120 degrees apart instead of 180, which wreaks havoc with transformers in welders and windings in electric motors.

The only option is to use a 208 -> 240 stepup transformer with a 208 VAC floating primary and a 240 VAC grounded center tapped secondary.

This is one reason, besides our 100 hp motor loads, that we went with 277/480.  All of our motors that are designed for 240 three-phase also run on 480.  Our shop lighting is 277 single phase.  And we use a 480 -> 240 transformer with a center tapped secondary for the split phase (welders, air compressor, etc).  The 480 -> 240 transformers are a dime a dozen and you can pick up a 25 kVA one for less than $1,000 bucks.  And you can get 45 kVA ones like this for about $2,000:
http://www.magnalight.com/showproduct.aspx?productid=64254&gclid=CLr3o4m96LQCFck7MgodxyMAGA

Going the other way with 208V to 240V often ends up overloading 208V wiring and that is the primary reason 277/480 is pretty much the standard now that has replaced the old high leg delta 240V three phase systems.  For a one-off system that doesn't have loads requiring 480 volt I would still find a 120/240 high leg delta generator instead of using 277/480 because it eliminates any transformers being you already have one winding in the generator tapped for a grounded neutral.  I would only use 120/208 as a last resort, as it is never installed anymore in new installations.
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« Last Edit: January 14, 2013, 11:55:46 AM by ChrisOlson »

smidy

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #44 on: January 14, 2013, 12:19:47 PM »
a little offtopic maybee, but is there any uppside with all this voltage 120-208-240-277-480V? up here in nothern europe it´s standard with 3 phase 400V to a normal house, ex we have 3*20A 400v to our house, the smal brewery i work on have 3*100A 400v. if it old grid problem that makes this warying in voltage, vy bother in off grid with all this voltage varying and not go for simple 400v 3 phase, i can see the problem with geting 230/400 volt 50hz stuff over there, but it seams its alot of truble with equpment that breaks and runs hot and so on, things i never heard of here, of course things brakedown here too, but you never need to think about if you have the right voltage att home when you buy eqipment, it is 230 or 400, 230 for 1 phase and 400 for 3 phase all you need to know is that you have enogth main brekers. but i guess i miss some thing.
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ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #45 on: January 14, 2013, 12:29:06 PM »
smidy,

The US has a hodge-podge of different "standards" that make no sense.  The European system is much more efficient and much better designed.  Somebody had a brainstorm that ended up being more like a brainstrain when they designed the split phase power system that is used in US and Canadian residential electrical services.
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Frank S

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #46 on: January 14, 2013, 01:01:12 PM »
Thanks Chris I'm glad there is at least one other who may think the split phase system is less than Ideal. in the US not even all power generation is 60hz At the power generation stations it ca nrange from 25 hz to 133 hz I think Niagara and the Hover project or the Columbia river power facilities are at the 2 extremes if memory serves.
 the 110v  got its roots with Edison his carbon filament bulbs worked best at 100v  then he patented a 3 wire DC system with 2 hots and a trot as I call it which was actually easily converted to the Tesla/Westinghouse AC system  I don't know why the split phase came to pass but I'm sure it had to do with someone making a ton of money off of it rather than providing electricity.
 The US history is full of brainfarts but to be fair so is the European     
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smidy

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #47 on: January 14, 2013, 01:06:27 PM »
then chris, you should have great ways to import 230/400 since your wife is from sweden  ;D. ofcourse it is problematic to go from contry standard if something fails and you have to import from over seas. i did se in your generatorsuport youtube that you have an european kitchen stove (not sure thats rigth world, that thing you make your food on) how do you power that thing? not sure but it have clock an timers? if so dont they get fast on 60hz or do you have 400v 50hz to in your armada of voltage?
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ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #48 on: January 14, 2013, 01:43:54 PM »
All the controls in my wife's range are DC and run off a small transformer in it.  All that had to be changed was the transformer and Electrolux put that in for export to the US.  The elements and Litz coils in it are 230V, which works fine on US 240 split phase by simply changing the cord and hookup to the power supply in it.  The European wiring has neutral and ground as the same thing with a 230V -> 24VDC 50 Hz transformer for the controls.  The US wiring separates the neutral from the ground and the legs go to the European "hot" and neutral and the ground goes to the frame.

The oven heating part doesn't know the difference between them.  It only took the 120V -> 24 VDC 60Hz transformer for the controls and the clock keeps perfect time.
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mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #49 on: January 16, 2013, 09:04:18 PM »
i own an acme 45kva 3ph/60hz transformer thats wired in at my shop and will be removed when we go. 

tag says
primary 240 delta w FC taps
secondary 208/120

can this be backfed from a 208 genset and feed out 240? ive seen a lot of people saying yes on electrician forums.

something i found out when i was looking at the transformer tonight, my digital meter claims around 146volts per leg on all 3 legs.  whats that about?

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #50 on: January 17, 2013, 08:50:07 AM »
I thought only Wile E. Coyote had them Acme transformers.  But yeah, you should be able to back feed it.

I assume you're measuring from leg to neutral with your meter?  I don't know what's up with the 146 volts.  You should get 120 from two legs to neutral, 200-208 on the high leg, and 240 between any two legs if it's a high leg delta system.  You should get 120 from all three to neutral, and 208 between any two legs, if it's a 208V wye system.

I'm guessing you got a measurement error there due to possibly the neutral carrying some power from unbalanced single phase loads, or a bad ground in the system.  Did you try measuring from neutral to ground to see if you get a voltage reading?

Why do you have a transformer with a 240 tapped primary and a 208 secondary?  I thought you currently have 240 high leg delta service?  You running something on 208V right now?  That type of transformer would typically only be installed where your utility company is stepping down 4800 or 7200 transmission voltage to 240 high leg delta three phase service for a "service block" where one transformer will feed several businesses with both single and three-phase power.  It'll be one of those big square buzzy suckers that sets on the ground someplace and says "DANGER - High Voltage" on it.  So then the high leg delta service comes into your factory or place, but you need 208V.  So you got your own transformer to step down the high leg delta "service block" to 120/208 45 kVA (200 amp service) for your factory or shop.
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« Last Edit: January 17, 2013, 09:00:48 AM by ChrisOlson »

mike_belben

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #51 on: January 17, 2013, 10:29:53 AM »
i meant a wall mounted digital killowatt meter so i can be billed accurately for electrical usage, not measuring with a multimeter.

 when i was negotiating the deal on my space, i said no to an estimated electric billing where im sharing lines with numerous other users.  especially since i knew thered be weeks or even months where i wasnt down there running anything.. the stuff i use there is sporadic.  i said if they put me on a meter then we had a deal, they said well do the meter but youll need a transformer, heres the specs.  i got lucky on a suitable unit way bigger than i needed and they wired it.  i didnt know anything about 3phase back then, it was all smoke and mystery.

ChrisOlson

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #52 on: January 17, 2013, 10:36:20 AM »
Yeah well - then it sounds like one of two things - your service block is 240 high leg delta, and since you wanted yours separate, you're on 120/208 already.

OR-

Your service block is 120/208 and you wanted 240 high leg delta for your place, so the transformer is being used in reverse to step the 120/208 up to 240 high leg delta for your shop.

Either way, you obviously already have a transformer, so your power problem is solved for your new shop and you can buy whatever generator you want.
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allenbee

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Re: starting from scratch in tennessee, offgrid machine shop.
« Reply #53 on: January 19, 2013, 12:01:25 PM »
Hello ya all... im in South Africa.
About off grid an living comfortably .
FIRST... cook with gas (until you can make your own), same gas or fire for hot water (once a day).
Forget air conditioning and use fans. (very light on battery bank).

Battery bank;
Contact me for 20 year guarantee lead/ acid battery bank. (normal price of 1 year guarantee battery).
12 V, 100 A/H through inverter for light, TV, computer, fans, cell charge etc.
Recharge by wind, solar, easy manual*, and manual fuel cell* . (*PATENT).

Designed for the poor of the world .
« Last Edit: January 19, 2013, 12:33:40 PM by allenbee »