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

[ChrisOlson]

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?

Up here they put a transformer on each phase for three-phase service. And they don't pay much attention to which phase they tap off of for single phase service drop. They usually tap off a single phase service on which ever wire is closest to the residence. And there's a couple places where they put in a transformer then run low-voltage 240V split-phase overhead to 5 or 6 houses with a single 50 kVA transformer, and hope the people don't all turn all their stuff all at the same time.

[ChrisOlson]

Chris I assume the POCO is a CooP? If so has anyone gone to the REA to file a complaint? CooP's get their funding from Uncle Sam in the form of low interest loans..

Plenty of complaints, but basically there's no money and no right-of-ways to run lines. The residences are so spread out that it costs in the millions to upgrade for just a few homes on one feeder. The towns like Hayward and Cable, or Ashland, have good power. But out in the rural areas it's pretty sketchy. People will complain one day about poor electrical service, then the next day they're all carrying rifles and shotguns ready to shoot anybody that tries to come on their property to string electric lines across it, or cut one of their trees down.

It costs any electric utility in the millions just to get an easement across all the private land, and even if they do win a day in court and get one they have to face gunfire in order to act on it. So nothing much has changed here in the last 40 years. There is not a place around here that doesn't have at least a generator. Farm & Fleet and Menards sells those worthless Generac 8 and 12 kW Guardian units by the trainload up here.

[bcroe]

3 phase transformer

A harmonic mitigating transformer also has a different winding
configuration where the phase angles (or vectors) will cancel out the harmonics on each
phase and reduce the current on the neutral wire. That reduces the amount of heat generated
as well as the losses in the transformers and actually saves the user by reducing the amount
of kW used.

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?
Bruce Roe

[Sunking]

They did it up here 40 years ago because back then there was only about 6 subscribers on it. It's never been upgraded as they added loads to it. So now the entire area browns out every time somebody turns something on.

Chris I assume the POCO is a CooP? If so has anyone gone to the REA to file a complaint? CooP's get their funding from Uncle Sam in the form of low interest loans. To qualify minimum standards must be followed and one of those is a +/- 10% voltage regulation. On a Single Phase service operating voltage is 250/125 so on the low end you are looking at 225/112 and 275/138 on the high end. All are within operating limits of any thing made or sold in the USA that is UL listed to use AC power.

[Sunking]

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.

Sounds like a good place for Moonshiners.

[ChrisOlson]

Heck at that distribution voltage I would expect a brown out if someone flushes a toilet. No wonder a lot of people up there have gone off grid.

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.

[SunEagle]

They did it up here 40 years ago because back then there was only about 6 subscribers on it. It's never been upgraded as they added loads to it. So now the entire area browns out every time somebody turns something on.

Heck at that distribution voltage I would expect a brown out if someone flushes a toilet. No wonder a lot of people up there have gone off grid.

[ChrisOlson]

I was surprised to see that any Utility would use 7.2kv for long distance power distribution..

They did it up here 40 years ago because back then there was only about 6 subscribers on it. It's never been upgraded as they added loads to it. So now the entire area browns out every time somebody turns something on.

[SunEagle]

Sorry I should have answered this. Let's use a real life example. Say a 480 Delta input transformer with Wye 208/120. Pretty typical setup in a commercial application. So lets say we load up Phase A to 100 amps line to neutral loads (120 volts). What is the current on the Delta Primary side?

Correct answer is Phase A = Phase B = Phase C = 8.3 amps. In a delta system all three phase currents have to be equal regardless if the secondary is balanced or not. The way to handle such a situation is to use what we call a K rated transformer which is made to be used on non linear loads where the neutral return conductor is larger than the phase conductors, and the core is made heavier to handle the extra heat generated.

Hope that helps.

A harmonic mitigating transformer also has a different winding configuration where the phase angles (or vectors) will cancel out the harmonics on each phase and reduce the current on the neutral wire. That reduces the amount of heat generated as well as the losses in the transformers and actually saves the user by reducing the amount of kW used.

[Sunking]

I don't see how putting the 3 phase Delta through 3 single phase transformers helps balance
phase loads. Bruce Roe

Sorry I should have answered this. Let's use a real life example. Say a 480 Delta input transformer with Wye 208/120. Pretty typical setup in a commercial application. So lets say we load up Phase A to 100 amps line to neutral loads (120 volts). What is the current on the Delta Primary side?

Correct answer is Phase A = Phase B = Phase C = 8.3 amps. In a delta system all three phase currents have to be equal regardless if the secondary is balanced or not. The way to handle such a situation is to use what we call a K rated transformer which is made to be used on non linear loads where the neutral return conductor is larger than the phase conductors, and the core is made heavier to handle the extra heat generated.

Hope that helps.

[Sunking]

I have made some incorrect statements myself. It happens to most of us.

I was surprised to see that any Utility would use 7.2kv for long distance power distribution. Usually that voltage is more for local or subdivision power. Usually you see 13.2kv or 13.8kv but even at that voltage 100 miles seems like a little too long to go. But hey I don't live up in Wisconsin so who knows what they use.

Not possible to do 100 miles at 13.2 at any usable amperage. REA's are limited to 10% losses. Typically for Rural you would transport power at 69, 135, or 750 KV to a local distribution transformer centrally located, then run 13.2 laterals. Late night last night so I messed that up. Came up last Wednesday to Dallas to celebrate my b-day and go to the OU/TX game. Time to go back to paradise.

[SunEagle]

I enjoy watching you shoot from the hip! Bruce

I have made some incorrect statements myself. It happens to most of us.

I was surprised to see that any Utility would use 7.2kv for long distance power distribution. Usually that voltage is more for local or subdivision power. Usually you see 13.2kv or 13.8kv but even at that voltage 100 miles seems like a little too long to go. But hey I don't live up in Wisconsin so who knows what they use.

[bcroe]

Well crap, that happens when you figure it in your head and forget to move decimal points.

I enjoy watching you shoot from the hip! Bruce

[Sunking]

I calculate 100A through 139 ohms (100 miles) drops 13,900 volts.

I don't see how putting the 3 phase Delta through 3 single phase transformers helps balance
phase loads. Bruce Roe

Well crap, that happens when you figure it in your head and forget to move decimal points.

[bcroe]

That is about the most ignorant statement you have said on this forum. Really a 7.2 Kv feeder for 100 miles huh? Most folks might believe that but that because they do not know what that means or how transformers work.

Distribution feeders run around 100 amps max, in some cases up to 200 to 300 amps. Over head lines utilities use are ASCR (Aluminum Conductor Steel Reinforced). A 100 amp feeder will use Code Trade name Robin a #1 AWG ACSR. Robin has an AC impedance of .268 Ohm's/Kft or 1.39 Ohm/mile. For 100 miles that is 139 Ohms. Worse case scenario If you were to fully load the conductor to 100 amps @ 100 miles away you would loose roughly roughly 140 volts on a 7200 volt line which is 1.9% loss. On a single phase 240/120 service you would expect a maximum 3 volt drop from no load to full load. NESC standard is +/-10%.

I calculate 100A through 139 ohms (100 miles) drops 13,900 volts.

I don't see how putting the 3 phase Delta through 3 single phase transformers helps balance
phase loads. Bruce Roe