Question about US mians system/power

[Tytonegro]

Hi, a rather technical question for US folks....

I have developed an automatic brew controller that is designed to work on 230V ac since I'm living in Europe. The small internal power supply that supplies the microcontroller is auto-ranging from 90 to 250V, so that would work straight away.



I was wondering if/how this would work in the US. I have heard there is a double/split phase system that you can use for heavy loads like washing maches etc. Not knowing anything about the details I'm looking for some advise or explanation about this.

So, in Europe 1 phase 230 V mains gives about 3000 Watt with 13 Amp. heater current.

In the US 115 V mains gives only 1500 W with 13 Amp heater current.

The split/double phase system would give 230 V again and therefore the same heater capacity as in Europe.

My questions are:

1. Is this double/split phase system available in all houses?

2. Is it just a matter of having the right plug to use a device on this split phase system?

3. Other remarks about it ....?

I saw that, for example, the Grainfather is sold in Europe 230V ac, 2000 Watt and in the US 120V 1600 Watt.

Thanks

 

[Wynne-R]

US mains voltage is three wire 120v/240v ± 5%. The vast majority of receptacles in US homes are NEMA 5-15r, which is 120v. https://en.wikipedia.org/wiki/NEMA_connector

240v is available in the breaker box but is generally used only for heavy draw appliances, loads in excess of 1800 watts. All-electric homes will usually have a 30 amp receptacle for a water heater and a 50 amp for the oven/range. If they use natural gas they probably don’t have those receptacles.

Basically, if you want 240 for anything else you have to add a dedicated circuit.

 

[Tytonegro]

US mains voltage is three wire 120v/240v ± 5%. The vast majority of receptacles in US homes are NEMA 5-15r, which is 120v. https://en.wikipedia.org/wiki/NEMA_connector

240v is available in the breaker box but is generally used only for heavy draw appliances, loads in excess of 1800 watts. All-electric homes will usually have a 30 amp receptacle for a water heater and a 50 amp for the oven/range. If they use natural gas they probably don’t have those receptacles.

Basically, if you want 240 for anything else you have to add a dedicated circuit.

Thanks that is very helpfull. So you can't assume that an average brewer might have access to 240V without specialist interventions, like an electrician changing the wiring.
In normal situations maximum capacity is limited to 1800 Watt (15 Amps) for US appliances if I understand well.

 

[nhamilto40]

The reality is a little more complicated: mains power in the US and Canada goes like this.

high voltage distribution (kV) -> transformer with center tapped secondary (120V-0v-120V) -> residential breaker box -> loads and receptacles

120V loads are wired between the center tap (0V) and either of the 120V leads. 240V loads are wired across both 120V leads. Receptacles can provide one or two of the 120V leads, optionally the center tap and a ground/protective earth.

The current residential standard receptacles are NEMA 5-15 (120V 15A or 20A with ground), NEMA 5-20 (120V 20A with ground), NEMA 14–30 (240/120V 30A with ground) and NEMA 14–50 (240/120V 50A with ground)

Some obsolete receptacles omitted the ground contact or abused the ground as a combined "ground and center tap". These practices ended in the 1970-1980 time period.

 

[Rhumbline]

Most homes in the US will probably have 240v for a dryer. I just bought a 240v Brew Boss system and i use the dryer plug to power it. The system I bought has a 5500 watt heating element.

 

[ajdelange]

The vast majority of single family dwellings in the US are wired with 200 Amp 120/240 biphase (as described above) service but it is not unusual to see larger service (600 or more) in larger homes (McMansions) of which we have many. Also, while the 240 V outlets are usually dedicated for special gear (compressor or other tools in the garage, clothes dryer, electric ovens or ranges...) it isn't much of a production to have an extra outlet for 240 installed especially if it is done in the space (garage, basement) where the panels are typically located. This is so common that the home improvement stores sell 'spa panels' which the home owner can take home and wire to his panel in order to accommodate a hot tub (though some jurisdictions require that a licensed electrician be retained to do the work).

The outlets in office, industrial and other large buildings (which I suppose would include apartment buildings) are usually wye connected across two phases (øøN) in a 3 phase service for 120/208.

Thus if you are providing a controller with a universal power supply (90 - 250 V also note 60 Hz here) you can be pretty sure people will be able to use it on their systems in the US and Canada.

 

[Tytonegro]

The vast majority of single family dwellings in the US are wired with 200 Amp 120/240 biphase (as described above) service but it is not unusual to see larger service (600 or more) in larger homes (McMansions) of which we have many. Also, while the 240 V outlets are usually dedicated for special gear (compressor or other tools in the garage, clothes dryer, electric ovens or ranges...) it isn't much of a production to have an extra outlet for 240 installed especially if it is done in the space (garage, basement) where the panels are typically located. This is so common that the home improvement stores sell 'spa panels' which the home owner can take home and wire to his panel in order to accommodate a hot tub (though some jurisdictions require that a licensed electrician be retained to do the work).

The outlets in office, industrial and other large buildings (which I suppose would include apartment buildings) are usually wye connected across two phases (øøN) in a 3 phase service for 120/208.

Thus if you are providing a controller with a universal power supply (90 - 250 V also note 60 Hz here) you can be pretty sure people will be able to use it on their systems in the US and Canada.

120V 200 Amps??!! Wow that's a lot of power: 24 kW
I live in Portugal where we live in an old (fashioned) small village house which has a 230V 16 Amp connection. Good for in total 3.7kW. That is at times a bit annoying, when we have to remember *not* to start the washing machine when making beer

Reading all this, I suppose I can offer my controller for the US market as well. The 60 Hz won't be a big problem, I have to adjust timings inside the software. I only have to check if the triacs will 'fire' properly when used on 120V

Any technically inclined ppl fancy being a beta-tester? PM me.

Thanks for all the info

 

[ajdelange]

Actually it is 200*220 = 44 kVA and, as I mentioned, many houses, including mine have more. My house is not a McMansion it has 3 panels of capacity 200 amps each. Of course only Al Gore actually consumes anything like that amount. The only heavy electric loads I have are emergency heaters (in the heat pump systems) and I think the biggest of those is perhaps 50 amps. In the US service size is determined by a formula of x kw/square foot + y% of large loads + AC +... The actual average load is a small fraction of the service capacity but on rare occasions the air compressor and multiple air condidtioners may kick on while the clothes dryer is running and madame has both electric ovens running...

WRT the triacs - people will most probably be using them with 220V heaters over here though some might use 120. It's the PIV that is usually of concern with such devices. If the gating pulses are derived from a universal supply there should be no problems with that. As I recall getting gating to work is a matter of forcing a minimum amount of current (small) into the gate.

 

[Tytonegro]

WRT the triacs - people will most probably be using them with 220V heaters over here though some might use 120. It's the PIV that is usually of concern with such devices. If the gating pulses are derived from a universal supply there should be no problems with that. As I recall getting gating to work is a matter of forcing a minimum amount of current (small) into the gate.

What is PIV??

The triacs are controlled via a an opto-triac. The opto triac will function normally, but the gate drive from the opto triacs to the power triacs might need other (smaller) resistors....

 

[The10mmKid]

What is PIV??

The triacs are controlled via a an opto-triac. The opto triac will function normally, but the gate drive from the opto triacs to the power triacs might need other (smaller) resistors....

PIV = Peak Inverse Voltage

 

[Tytonegro]

PIV = Peak Inverse Voltage

Ahh, ok, Thanks
With 800 Volt triacs that won't be a problem

 

[ajdelange]

The triacs are controlled via a an opto-triac. The opto triac will function normally, but the gate drive from the opto triacs to the power triacs might need other (smaller) resistors....

Should be easy enough to find out if there is a potential problem. Operate your system as you normally do but double the gate series resistor. This will halve the gate current to what it would be if operated with a 120 V load. If it works with double the resistance, treble it. If it works with three times the normal resistance (1/3 the normal gate current) then I think you will be OK with 120 V loads but as I said the vast majority of users over here have 220 V heaters.

 

[Tytonegro]

Should be easy enough to find out if there is a potential problem. Operate your system as you normally do but double the gate series resistor. This will halve the gate current to what it would be if operated with a 120 V load. If it works with double the resistance, treble it. If it works with three times the normal resistance (1/3 the normal gate current) then I think you will be OK with 120 V loads but as I said the vast majority of users over here have 220 V heaters.

Yes that is one good option, but I also will use a big transformer 230 -> 115V to test. (Type of transformer ppl use when changing country...) that will also test the power supply...

 

[dcbw]

Also a lot of people have 120V 20A outlets in their kitchens for things like microwaves and refrigerators. So you have 3 common options:

120V/15A (everywhere)
120V/20A (80% ? of kitchens)
240V/30A (electric clothes dryer outlets, often in basements)

As mentioned, the 120v receptacles are 3 wire single phase (hot, neutral, ground). The 240V ones are 4 wire two phase (hot A, hot B, neutral, ground). Sometimes they are only 3 wire missing ground if they are old.

 

[ajdelange]

A modern (or old) 240 V outlet will be 'missing' the neutral i.e. it has just the two hots and the grounding conductor (bare or green). There was an exception (no longer allowed) in the grounding rules which allowed the neutral to be used as the grounding conductor in ranges and clothes driers. Because of this one sometimes finds, in older construction, 240 V outlets missing the grounding (earth) conductor.