WE Energies to Squash Distributed Renewables with their latest rate case.

[SunEagle]

Off-grid is the only practical solution for many cabins and part-time or seasonal homes here. Most of the weekend cabins just have a generator with a few batteries and an Outback inverter with a transformer on it to run a well pump. Few of the weekenders have solar or wind power.

Many years ago they were going to run a big transmission line from someplace down south to Duluth. They had problems with people setting up on hillsides a mile or more away with a Barrett 50 and shooting the insulators off as they were trying to build the line. The line crew quit the day a lineman was working on a pole and suddenly an insulator right next to him exploded, thanks to a 500 grain, 50 caliber Browning Machine Gun round that came from a hillside like a mile away. They pretty much abandoned the whole idea because the Scandinavians that live up here are a little on the independent side, and the rest of it is Indian Reservations along with 1.5 million acres of woods in the Chequamegon.

I have shot a Barrett 50 single shot version. Definitely is loud and impressive.

Not something I would hunt with and I doubt I could see a target at 1 mile even with my Weaver classic extreme.

[Sunking]

I'm no expert on transformers, but I believe this is about a transformer with a single iron core
(with branches) common to different windings for all phases? Not 3 separate transformers?

Actually it can and has be done with three separate transformers. Anyway maybe a picture well answer your question.

Left side a WYE transformer like 208/120 where you can take power from Phase-to-Phase which is 2098 volts, and on the right is Delta. Take note either can be made with separate transformers, just a matter of wiring it together. A good example to use 3 transformers is when you cannot fine a 3-phase of high enough power, or will not physically fit in the designated space. They are real easy to spot if you know what you are looking for on distribution lines. Up on a pole you will see 3 transformer side by side.

[Sunking]

Not something I would hunt with and I doubt I could see a target at 1 mile even with my Weaver classic extreme.

Hunt with a Barret? Well maybe Elephants and Grizzly Bears. But its primary purpose is for hunting men or women, not animals. I can just see Bambi getting shot in the shoulder with one. Not going to be much eatable meat left.

[ChrisOlson]

Hunt with a Barret? Well maybe Elephants and Grizzly Bears. But its primary purpose is for hunting men or women, not animals. I can just see Bambi getting shot in the shoulder with one. Not going to be much eatable meat left.

People use them for silhouette shooting. 1,000 and 2,000 meter competition. One of our neighbors who is big into silhouette shooting has a custom one with a 44" Freshour barrel and too many other modifications to even remember what he told me about it. The optical sight alone on it cost over $10,000. He can shave the hair off the balls on a flea with it at 1,000 meters. The balls on a squirrel ain't safe at 2,000.

[inetdog]

Actually it can and has be done with three separate transformers. Anyway maybe a picture well answer your question.

Left side a WYE transformer like 208/120 where you can take power from Phase-to-Phase which is 2098 volts, and on the right is Delta. Take note either can be made with separate transformers, just a matter of wiring it together. A good example to use 3 transformers is when you cannot fine a 3-phase of high enough power, or will not physically fit in the designated space. They are real easy to spot if you know what you are looking for on distribution lines. Up on a pole you will see 3 transformer side by side.

Dereck,
What you have illustrated is how you can connect any number of single phase loads to a three phase system.
But if you do the circuit analysis, an unbalanced single phase load (say from S to N on the left) will be converted into an unbalanced load which appears only between two line on the right.
The transformer, handy as it might be, cannot convert a single unbalanced load on the left into equal (balanced) line currents on the right side.

The original assertion was that you could not possibly wire a single single phase load on a service in such a way that POCO sees a balanced load (equal line currents). Instead POCO must take a statistically useful number of single phase customers and distribute them evenly across the three line-to-line phases (if delta) or the three line to neutral phases (if wye) to balance the load on their generating facilities.

To do that power distribution over the three phases requires either an active power converter with DC in between or a rotary converter (motor generator) where the driving force is taken equally from all three phases regardless of the balance on the output, load, side.

This question is totally separate from the question of cancelling out triplen harmonics by converting them to circulating current in a delta, which is not seen by the generating equipment.

[ChrisOlson]

The original assertion was that you could not possibly wire a single single phase load on a service in such a way that POCO sees a balanced load (equal line currents).

To do that power distribution over the three phases requires either an active power converter with DC in between or a rotary converter (motor generator) where the driving force is taken equally from all three phases regardless of the balance on the output, load, side..

That is correct. You cannot run a balanced three-phase generator or source with unbalanced single-phase loads on it. Never in my experience have I seen it.

The more common use for rotary phase converters is to convert single phase service to three-phase. They are quite common in rural areas for irrigation pumps where three-phase overhead service is not available. A three phase motor can be wired to provide three-phase service from single phase, without using a separate motor and generator. Although the motor requires an external inertial starter to get it running.

[SunEagle]

That is correct. You cannot run a balanced three-phase generator or source with unbalanced single-phase loads on it. Never in my experience have I seen it.

The more common use for rotary phase converters is to convert single phase service to three-phase. They are quite common in rural areas for irrigation pumps where three-phase overhead service is not available. A three phase motor can be wired to provide three-phase service from single phase, without using a separate motor and generator. Although the motor requires an external inertial starter to get it running.

We have a 50HP American Rotary Phase converter system here in our lab to convert 240v single phase to 240v 3 phase. It does a pretty good job running our large AC unit and provides 3 phase power for all our transformer tests.

[ChrisOlson]

We have a 50HP American Rotary Phase converter system here in our lab to convert 240v single phase to 240v 3 phase. It does a pretty good job running our large AC unit and provides 3 phase power for all our transformer tests.

Yep, I have a small 5 hp rotary phase converter made from a Baldor three-phase motor to run my three-phase lathe and vertical mill from our 240V split-phase inverter.

[bcroe]

We have a 50HP American Rotary Phase converter system here
in our lab to convert 240v single phase to 240v 3 phase. It does a pretty good job running
our large AC unit and provides 3 phase power for all our transformer tests.

50 HP is a huge single phase load. I built this 7.5 hp for my neighbor a while back; now
I need to find an old 5 hp 3 phase motor to make one for my Bridgeport. Bruce Roe

[kwilcox]

Not sure I'm understanding completely... You are slaving a three phase motor to a single phase motor to use it as a three phase generator? Damn... I've got some potential workshop improvements to make if that's the case. What's the efficiency?

[bcroe]

Not sure I'm understanding completely... You are slaving a three phase motor to a single phase motor to use it as a three phase generator? Damn... I've got some potential workshop improvements to make if that's the case. What's the efficiency?

No, nothing that efficient. No single phase motor. Here a pair of 240V leads are fed to 2
phases of a 3 phase unloaded motor. Some oil capacitors feed power to the motor 3rd
input. Extra caps are switched in temporarily to get it started. The motor flywheels the
power to the third phase. Then the 3 motor terminals are available to run a regular loaded
3 phase motor, perhaps at somewhat reduced power.


Some phase converters have built without the extra motor, but the load motor power
is much reduced. Lots of info available on the internet. Bruce Roe

[SunEagle]

50 HP is a huge single phase load. I built this 7.5 hp for my neighbor a while back; now
I need to find an old 5 hp 3 phase motor to make one for my Bridgeport. Bruce Roe

The equipment is where I work. We use that system to test a number of harmonic mitigating transformers and harmonic filters. We also measure the power quality affects of non linear loads using a number of Fluke and Dranetz meters.

I can see the benefits of having a 3 phase power source at your home workshop. You can run some nice big "tools" with it.

[ChrisOlson]

Not sure I'm understanding completely... You are slaving a three phase motor to a single phase motor to use it as a three phase generator? Damn... I've got some potential workshop improvements to make if that's the case. What's the efficiency?

Not sure of the efficiency. But you take a regular three-phase 208/240/480V motor and wire it parallel wye for 208/240V. There are three pairs of leads that normally go to the three-phase power source, call them T1, T2 and T3. You wire 240V split-phase to T1 and T2. You wire run capacitors between the T1-T3 and T2-T3 leads. You get three-phase power from the T1, T2 and T3 leads for your three-phase loads.

The phase converter motor won't start by itself. As Bruce said you can use a start capacitor. Or on mine I have a little 1/4hp 120V motor that I use to start it with and spin it up. The phase separation isn't quite perfect because the split-phase source is 180 degrees out of phase instead of 120. So the idler motor makes a little noise until you start your three-phase load, then it smooths out because the load motor also acts as a rotary phase converter and helps even out the amps and phase separation on the legs.

I built mine from a 5hp Baldor motor and it runs my lathe and vertical mill just fine using either our 240V inverter, generator, or the inverter in generator support mode where both the inverter and generator are supplying power to it. It won't, however, run my three-phase Miller Pro MIG welder without starting either the motor in the lathe or the mill to clean up the power a bit.