Why isn't EVERYTHING 3 phase 480v

[mmason7764]

I'm enjoying all the discussion and history.

Another angle: electric motors are sized with amperage being the primary factor. As horse power goes up, the amperage goes up until it gets to the point the amperage is so high it's a pain in the *** to conduct. The solution is to increase the voltage. Increased voltage requires better insulation, but it's worth the extra cost to get the amps down.

When electric motors get to be several hundred horse power even 440V 3 phase requires too much amperage. I forget the voltage that was used on the 300 and 500 hp motors the last place I worked but I remember a little above 2000 volts.

So, everything is a tradeoff. The most economical solution to any load is give it the optimum voltage, amperage, and number of phases. Most house stuff, 120V AC single phase, 60 hz. Bigger loads, 240 V. The next step is more phases, 3 is the optimum. Etc.

Mark

 

[r_olson_06]

I'm enjoying all the discussion and history.

Another angle: electric motors are sized with amperage being the primary factor. As horse power goes up, the amperage goes up until it gets to the point the amperage is so high it's a pain in the *** to conduct. The solution is to increase the voltage. Increased voltage requires better insulation, but it's worth the extra cost to get the amps down.

When electric motors get to be several hundred horse power even 440V 3 phase requires too much amperage. I forget the voltage that was used on the 300 and 500 hp motors the last place I worked but I remember a little above 2000 volts.

So, everything is a tradeoff. The most economical solution to any load is give it the optimum voltage, amperage, and number of phases. Most house stuff, 120V AC single phase, 60 hz. Bigger loads, 240 V. The next step is more phases, 3 is the optimum. Etc.

Mark

I have done a few 600hps at 480 and 1 700hp at 480 and it no fun at all 3 to 4 runs of 500kcmil cu. Trying to tuck in a pecker head with 4 motor leads per phase. The next step is usually 4160v from what I recall.

Sent from my XT1080 using Tapatalk

 

[Lassen Forge]

3ø 480 is awesome, but it costs more to install... 3 transformers instead of one for each service line. An extra conductor to, what, 65%+ of the places that don't have 3ø, then you run into the issue of Delta or Wye...

I, personally, would dig it, but I don't think the power company would be too thrilled by it. Just my 2¢...

 

[1Garageman]

My bagels would get done even faster every morning in the 480 toaster oven!

 

[ddawg16]

You do not have 2 phases coming into the house. It is single phase 240, which is center-tapped.

Line to ground voltage is 120V while EU line to ground voltage is 230V.

I should have been a little clearer.

They use 2 phases of the 3-phase to give you the single phase at your house.

 

[Farmall450]

Extension cords are already spendy imo

 

[Gmonkee]

Why not 480?

In a home with the skills of the average home owner..... I see dead people.

 

[Lelandwelds]

I don't have a good answer myself, but I don't think that is it. Europe has 250v domestic outlets. 250 vs 277 ain't much difference.

Take 240 volt and short out one wire and thats 120 volts. Short one wire of 277 volt you have 277 volts. 277 is a lot more than 120 volt

I have never been to Europe and if I go, I will not be working on ANYTHING. But, I believe they get their 250 volt from two hot legs just like most of the US. So, one leg to ground is 125 volt. 277 is more than 125.

The post about 3 phase types is the cleanest explaination I have ever read. Someday I might even understand. I am mostly about flip switch and it works.

 

[Lassen Forge]

Where I am (sometimes) at in italy, the line is 1ø 230 (give or take), just like here. The color codes are different, and when you work with those tiny, tiny wires it really gets you wondering, but nothing inherently more unsafe with their 230 as our 120... I *have* been bit by it (more than once, actually), I will tell you it does bite a *bit* harder, but the weird thing isn't the higher voltage, it's that 50hz... seriously, getting bit by that feels ultra-strange... and your muscles hurt a bit more... but it's not as "instantly fatal" as some would have you believe.

 

[dogdog]

 

[thickhead]

For some odd reason my brain is trying to picture a 3 phase 480v version of the electric hedge trimmer out in the shed. Could be a good thing right?

 

[decableguy2000]

I should have been a little clearer.

They use 2 phases of the 3-phase to give you the single phase at your house.

No, 2 wires hot and neutral, 7200 or 13k volts to the transformer has 2 tap legs 120 on each leg. Where I'm at, I'm a couple of miles from 3 phase, and 3/4 from 2 phase power.

 

[joeswamp]

I should have been a little clearer.

They use 2 phases of the 3-phase to give you the single phase at your house.

No, 2 wires hot and neutral, 7200 or 13k volts to the transformer has 2 tap legs 120 on each leg. Where I'm at, I'm a couple of miles from 3 phase, and 3/4 from 2 phase power.

Exactly, house voltage is typically sourced from a single primary or phase. In my old neighborhood with overhead wires, we only have one primary running down our small street -- you can see it on the pole. If you walk over to the main (busy) street you see the three primaries and you also see the three transformers mounted on a pole sending three phase power to the gas station, for example.

In a modern industrial building you typically don't get 240V single phase, like you get in your house. Modern low voltage three phase is 208V between phases and 120V to ground, so the 120V outlets are sourced from the individual phases. In my company's newly constructed building we had to install an additional transformer for the rare case of using a 240V single phase device.

Old fashioned three phase is 240V delta, so you can get 240V between two phases (if you already have three phase). When you buy old used machine tools they were usually designed to run at the older higher voltage and there are sometimes issues running them at 208.

 

[marcone]

I live in Europe and have 8KW 3 phase residential power installed, it's no big thing and it does not cost additional aside from the extra cost of wire from the distribution box to your home and load balancing in the home. That is because all the power infrastructure is 3 phase from the power plant down to the residential distribution box.
Almost anything with current draw of more than 3000W is available also as 2/3 phase model.
Regarding voltages, between any phase and ground you have 230V and between any 2 phases you have 400V.

 

[Lassen Forge]

I live in Europe and have 8KW 3 phase residential power installed, it's no big thing and it does not cost additional aside from the extra cost of wire from the distribution box to your home and load balancing in the home. That is because all the power infrastructure is 3 phase from the power plant down to the residential distribution box.
Almost anything with current draw of more than 3000W is available also as 2/3 phase model.
Regarding voltages, between any phase and ground you have 230V and between any 2 phases you have 400V.

Same with us in Umbria. 230 primary, 400 secondary.

The hard part (for me) was being used to the "unlimited" tiered power in the states (you can use as much power as you want, you just pay for it) and having the "limited by KW draw" power slap us in Italy.

We had iirc originally set up for "standard" 2.4 KW service to the house, but later ran a separate leg to power up the (new to us) shop and outbuilding... all was fine until we were cooking dinner, and washing clothes, and I turned on something (drill press, grinder, or somesuch) and we tripped our mains. I reset it twice, then had to call ENEL before they would let us reset it again. And was told ( ) we should have known better by the "nice" lady at ENEL...

After we got that straightened out, we ended up upgrading to 5KW service (it took them all of 30 seconds while we were on the phone - VERY cool) and no problem (other than higher bills, of course!). But it was a HUGE culture shock for those new to living over there.

 

[Bigwheels]

I purchased a european bridge saw with 3 motors 1 10hp and 2 5hp. The power company quoted me 7500.00 to bring the required 3 phase to my shop so I opted for a phase converter now 15 yrs later ive spent over 10k on rebuilding or replacing the phase converters. wish i would have ponied up in the beginning. Not to mention how much profit lost during down times. Just saying it was an expensive proposition no matter how i went about it.

 

[u3b3rg33k]

Same with us in Umbria. 230 primary, 400 secondary.

The hard part (for me) was being used to the "unlimited" tiered power in the states (you can use as much power as you want, you just pay for it) and having the "limited by KW draw" power slap us in Italy.

We had iirc originally set up for "standard" 2.4 KW service to the house, but later ran a separate leg to power up the (new to us) shop and outbuilding... all was fine until we were cooking dinner, and washing clothes, and I turned on something (drill press, grinder, or somesuch) and we tripped our mains. I reset it twice, then had to call ENEL before they would let us reset it again. And was told ( ) we should have known better by the "nice" lady at ENEL...

After we got that straightened out, we ended up upgrading to 5KW service (it took them all of 30 seconds while we were on the phone - VERY cool) and no problem (other than higher bills, of course!). But it was a HUGE culture shock for those new to living over there.

2.4kW is... a single 10A 240V circuit? i couldn't even run my dryer!

Remote control of your main breaker would never fly in the US. people here will shoot at the power company for trying to swap out mechanical meters for electronic ones!

I have 19kW service, and most newer houses have 38kW service. of course if you actually use more than 45,000kWh/yr you may find yourself on another rate plan.

 

[Ohmthis]

2.4kW is... a single 10A 240V circuit? i couldn't even run my dryer!

Remote control of your main breaker would never fly in the US. people here will shoot at the power company for trying to swap out mechanical meters for electronic ones!

I have 19kW service, and most newer houses have 38kW service. of course if you actually use more than 45,000kWh/yr you may find yourself on another rate plan.

Remember that their power is 3 phase so that would be 10a per phase. Depending on the voltage, which has been stated as 230v per phase and 400v phase to phase. That's a lot of power.

 

[manioso]

[Quote:
Originally Posted by u3b3rg33k View Post
2.4kW is... a single 10A 240V circuit? i couldn't even run my dryer!

Remote control of your main breaker would never fly in the US. people here will shoot at the power company for trying to swap out mechanical meters for electronic ones!

I have 19kW service, and most newer houses have 38kW service. of course if you actually use more than 45,000kWh/yr you may find yourself on another rate plan.
Remember that their power is 3 phase so that would be 10a per phase. Depending on the voltage, which has been stated as 230v per phase and 400v phase to phase. That's a lot of power.]



10amp per phase at 230 volt is 4kw (10a x 230v x 1.73).

 

[bonneyman]

480v toasters would be awesome

I could get charred toast fast - 120 volts per slice!

 

[FJ 432]

I could get charred toast fast - 120 volts per slice!

Yep but if the slice gets stuck and you need to jab a fork to free it up....BAM...no more worries.

 

[ruffryder]

10amp per phase at 230 volt is 4kw (10a x 230v x 1.73).

Using the square root of 3 (1.73) requires you to use the line to line voltage of 400 v for your calculation method, total of around 7kW.

 

[metalmad]

Wow....some of the responses are funny.....

Actually, both the US and Europe have the same voltage.

We all have 240 going to our houses.....the US just happens to use the neutral so we can get 120 Vac.

Anyone get bit by 240? Not fun. Try 480. Better yet, don't. You most likely won't be able to tell us how it felt.

In reality, everyone has 3 phase available at the pole....the transformers for your house only use two of the phases.

When you get down to the small motors found in the typical house, there is no cost/performance advantage to running them off 480. Compounding that, keeping all of your motors phased properly would be a real *****. You buy a new vacuum? 50/50 chance the motor will turn the way you want it to. Anyone who has done commercial work with 480 3-phase motors knows what its like to 'bump the motors' to check for rotation.

The comments about the light bulb above? Good lord...**** is getting deep.

Surprised no one asked by we have 60 Hz and everyone else 50 Hz.

We use the neutral in Europe, in the UK our supply voltage is 230V +/-10%, generally around 240V, depending on how far from the local substation we are. Most streets run 3 phase power underground, with house generally run on different phases to avoid a mass power outage (well unless the substation trips / loses its supply) i.e. House A Phase 1, House B Phase 2, House C Phase 3, House D Phase 1, House E Phase 2, House F Phase 3 and so on.

Because of that its often possible to ask for a supply upgrade to 3 phase, albeit the cost can vary wildly depending on cable requirements and substation loadings.

Our 3 Phase is 400V +/- 10% so we generally see 415V and the Europeans see 380V, phase colours are Brown, Black, Grey and a blue neutral (used to be Red, Yellow, Blue with a black neutral)

 

[metalmad]

Also in the UK, we have cutout fuses in the service head at the house end.
DNO (power company) split off the 3 phase line in the street and bring a line and a neutral core cable to the house (on their side the neutral and earth/ground wire are bonded together)
At the service head the line/live/hot is fused - generally 60/80/100amps (though there are still some 40 and 125amps around), neutral and earth are split, live and neutral then go through the meter and to the distribution box / fusebox.
We get billed standing charge (daiiy charge) and charged per Kwh unit
One problem here is in 1963 flexible cords were harmonised with the rest of europe as brown (live), Blue (neutral) and green with a yellow stripe (earth) partly so people with red/green colour blindness wouldn't put themselves or others at risk swapping a plug over. Fixed wiring (stuff that connects sockets/light fixings to the fusebox) though wasn't in the UK until 2004/2006 and it was the old system of Red (live), Black (neutral) and Green (earth).....which means we now when we do a fusebox upgrade have to put a sticker on the panel saying "This installation contains wiring to 2 versions of BS7671, great care should be taken when identifying conductors" (BS7671 is the UK version of the NEC, basically the bible electricians work to.

 

[notlob]

 

[MikeF2316]

Using the square root of 3 (1.73) requires you to use the line to line voltage of 400 v for your calculation method, total of around 7kW.

[Quote:
Originally Posted by u3b3rg33k View Post
2.4kW is... a single 10A 240V circuit? i couldn't even run my dryer!

Remote control of your main breaker would never fly in the US. people here will shoot at the power company for trying to swap out mechanical meters for electronic ones!

I have 19kW service, and most newer houses have 38kW service. of course if you actually use more than 45,000kWh/yr you may find yourself on another rate plan.
Remember that their power is 3 phase so that would be 10a per phase. Depending on the voltage, which has been stated as 230v per phase and 400v phase to phase. That's a lot of power.]

10amp per phase at 230 volt is 4kw (10a x 230v x 1.73).

2.4 kW is 2.4 kW, no matter what your voltage is. If you have higher voltage, more phases, it doesn't matter, your current will just go down. 2.4 kW will not run a North American drier. (I assume the rest of the world's driers are the same.)

My parent's first drier had the option to be wired for 120. It had 2 heater elements that could be connected in series for 120 volts or parallel for 240. Presumably you'd slow the fan motor down to get the temperature up a bit. Needless to say, it wouldn't have been very good at 120.

 

[sam.coll]

NZ/Australia 230V phase to neutral/earth, 400V phase to phase. 2-wire single phase (phase conductor + neutral conductor) or 4-wire three phase (P1, P2, P3 conductors + neutral conductor) its all pretty basic all distribution transformers are WYE on the secondary side no high legs, delta etc. 4-wire 3 phase distribution lines or underground cables run down every suburban street with high voltage 3 phase (think in the US they call it primary) usually of 11000V or 22000V (3 wire)

 

[danski0224]

I worked in a coal fired power plant once, and there were several 7700V motors that I got to see, so that must be better than 480V.