The OPPD meter through which runs the single-phase 240V electricity to run our house and power our plug-in Prius.
How to Power the Plug
By Bill Moore
This month's ePoll question (check the home page, right-hand column, about half way down) asks whether or not readers have access to 240 volt electric power to more quickly charge a future battery or plug-in hybrid car. Not being an electrician, I incorrectly phrased the question by asking if you had access to 3-phase, 220 V electric power. Turns out, there is no such animal. 3-phase is strictly an industrial rating to run big motors, welders and such and it comes in flavors of 240 or 480 volts. Typical residential wiring is single-phase 240 and 120V, as Mike Harrigan notes in an email he sent me this afternoon. I found it so helpful that I decided to reproduce it here, along with the link to Martin Eberhard's blog and spreadsheet.
So, with my apologies for the confusion, here is Mike's explanation of what you need to be looking for when figuring out how you'll someday recharge that Volt, Leaf or Tesla Model S.
I just read your latest EV World update and have a comment regarding 230v power. You don't need 3-phase power to charge a car battery. Your article implies that 230v and 3-phase are synonymous, which they are not.
Few, if any, homes would have access to 3-phase power. The power available in residential homes is typically 120v and 240v, both single-phase. Most homes have either 100 amp (older homes), 200 amp (newer, normal size homes), or 400 amp (newer, larger homes) 240v single phase service. The transformer that feeds your house has three wires, let's call them A, B, and N. The A & B wires are fed from the two ends of the transformer winding and provide 240v service. All of your high power appliances such as stoves, ovens, clothes dryers, pool pumps, air-conditioning compressors, etc. use the 240v service. The rest of your house electricity is 120v service that is provided by either an A-N or B-N connection. The N (neutral) wire comes from the middle of the transformer winding, therefore 120v (half of 240) is provided across the A-N and B-N connections. Often the A, B, N connections are confused with 3-phase power, but it is actually completely different. The transformer feeding your home is using only 1 of the 3 phases that are generated by electric generation plants. Commercial establishments that use high power often have real 3-phase power and it certainly is possible to develop a car charging device that uses 3-phase power, especially if we are going to have high-power chargers that provide 100+ kW of charging power.
OK, so that's probably more than you wanted to know about power. However, here is something you will find useful and you might want to share with your readers. Martin Eberhard (Tesla founder and former CEO ) developed a spreadsheet that allows you to do a survey of your home electrical system to determine how much spare capacity you have for charging your EV. Since I was the VP of Service and Customer Support for Tesla at that time, we distributed the spreadsheet to our customers in preparation for the installation of their EVSE (charger system). Please note that it's not as simple as adding up all your electric loads. The NEC (National Electric Code) includes duty cycle data that takes into account the fact that your electrical appliances aren't all on at the same time.
OK, spreadsheet is attached. But for complete information you should steer your readers to the blog that was created by Martin which also has a link to download the spreadsheet. The blog explains in more detail much of what I've already said in this email plus has instructions on how to use the spreadsheet.
Mike is the VP of Sales & Marketing for Atieva Inc., but formerly worked for Coulomb Technologies and prior to that Tesla Motors.
Published: 03-Nov-2009 | Page Views: 1524
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Reader Comments
5 comments so far...
1.
04-Nov-2009
95376
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Three phase is three 120 volt lines,a nuetral and a ground.
Posted by: john hurt
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2.
05-Nov-2009
95893
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Sorry John but three phase is not as you say. You would be hard pressed to find any power at 120 three phase. You can obtain 120 in a three phase system but no commercial devices are produced to operate on 120 vac 3 ph. Also be aware that 240 vac 3 ph and 480 vac 3ph are in many areas far less common than 208 vac 3ph. Lite commercial for 208 and heavier industrial for 480. Also be aware that depending on whether or not you have a delta or wye system of 3 ph a neutral may not be available or needed. In a 480 vac 3 ph system there is also available at times 277vac.Commonly referred to in the trades as A WILD LEG. Commonly used in industrial lighting systems. Any or all of these sources can be used to charge batteries. Just depends on how you hook em up
Posted by: Lawrence ELLIOTT
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3.
05-Nov-2009
96101
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I was under the impression that this web site was not only for people in the United States. Although it's true that here in the U.S., few homes have access to 3-phase power, that's not true the world over. In Sydney, Australia, many homes have 3-phase power. For motors exceeding about 1/2 horsepower, 3-phase is better, and central air conditioning systems have motors bigger than that. It is probably for that reason that residential neighborhoods in Sydney have 3-phase power available - they use it for air conditioning.
Not all 3-phase systems are the same either. There is a difference between delta and wye, but probably there is no need to explain that here.
In much of the world, 120 volts is not provided. Instead, homes have only 240 volts. In those countries, having 240 volts available to recharge electric cars is not a problem. However, even in those countries, standard receptacles generally provide a maximum of about 15 amperes, so to recharge an electric cars really quickly, they would still need special receptacles.
Posted by: Frank Eggers
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4.
06-Nov-2009
96505
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Hi Bill,
North America has a fundamental electrical distribution problem in that it is based on single phase 120 V ac, where most of the rest of the really developed world (including Europe, China, Africa, Russia, Asia (except Japan), UK, half of South America etc http://users.telenet.be/worldstandards/electricity.htm uses 230 V ac as part of a 3-phase 400 V ac between phases, which is extensively used for residential dwellings as these phases are offered as single phases to alternate houses.
If ever the USA needed a non-military stimulus package then the re-wiring of the USA, Mexico and Canada to 3-phae 230 V is staring them in the face!
If a developed world house needs 3-phase, then they link onto the 4 wires (including the neutral) from the street wiring. We in Australia extensively use air conditioning to keep cool and a high proportion of the air conditioners are 3-phase because these motors are far more efficient (thanks Tesla).
Because the 3-phase voltage is nominally 230 V not 120 V (as in North America) the total current drawn is about a third what is drawn residentially in North America, and we have three (120 deg) phases not two (180 deg) as in North America, this three phase distribution supply is can easily handle about 500 residences per transformer where North America is limited to about 120 residences per transformer if you are lucky before the street wiring loses too much power in the lines.
When it comes to powering EVs the rest of the developed world is one step off having the 3-phase infrastructure already in place, and my house is wired for 3-phase! :)
Posted by: Malcolm Moore
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5.
06-Nov-2009
96937
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Interesting article but full of mis-information.
120VAC has forever been referred to 110 or 115 VAC
and 240VAC has also been logically called 220 or 230VAC and I don't see anything wrong with that since so many people all around the country have tiny differences in opinions and perceptions. Also
not "ALL" large appliances are operated on 240VAC.
Don't sweat the small stuff and don't argue with anyone over it. Make jokes and laugh about. The only ignorant ones are those who make fun and criticize over simple mistakes or typo's.
Posted by: marv howse
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