How does 120, 240 and 440 circuits work?

by SPL Tech
Tags: circuits, work
 P: 5 I am looking for a web site that explains how 120, 240 and 440 volt circuits work. I am refereeing to the ones you have in your house and such. I am trying to figure out how they get 240 volts from 120 and such.
 P: 15 Somebody might tell you here, but if you search two things on google you'll be alot more prepared to understand any of their answers: First, search "voltage amperage resistance" Second, search "transformers" You'll need the first to understand the second.
 P: 173 A great site to start with would be to visit http://howstuffworks.com They have great articles on power grids ond household circuits. Do a search on electricity at the top of the page. For your last question... Most houses in residential areas have 240 volt, 200 amp service that is transformed down from a very high voltage from the power company. Power companies use the high voltage for power transmission because it is more efficient. From that you are able to supply devices in your house with either 120 volts or 240 volts. The 240 volt service contains two 120 volt wires, a neutral wire and a ground. To get 240 volts to an appliance, you connect both 120 volt wires to get a 240 volt potential. To get 120 volts to say a lightbulb, you would connect a single 120 volt lead and the neutral wire (which is at ground potential).
P: 5

How does 120, 240 and 440 circuits work?

 Quote by triden A great site to start with would be to visit http://howstuffworks.com They have great articles on power grids ond household circuits. Do a search on electricity at the top of the page. For your last question... Most houses in residential areas have 240 volt, 200 amp service that is transformed down from a very high voltage from the power company. Power companies use the high voltage for power transmission because it is more efficient. From that you are able to supply devices in your house with either 120 volts or 240 volts. The 240 volt service contains two 120 volt wires, a neutral wire and a ground. To get 240 volts to an appliance, you connect both 120 volt wires to get a 240 volt potential. To get 120 volts to say a lightbulb, you would connect a single 120 volt lead and the neutral wire (which is at ground potential).
I am well aware of what the four main electrical properties are. I am a car audio installer / SPL competitor. Anyway I know that the main lines in your house come on two 120-volt hot wires and one neutral wire. I am looking for a little more “in depth” or advanced explanation then that. I am looking to know how they get like 208, 220, 440 and 480-volt lines. Also regarding the two hot 120VAC lines that come into the house, how do they get 240 out of them? In the automotive industry we can simply series electrical circuits to double the final voltage of the circuits. Like for example we can series two 12-volt battery to get one 24-volt battery. Obviously that’s not how its done in houses because you can not really series two positively charged lines. Also I am interested in how then get those weird voltage levels, such as 230 volts and 208 volts and whatever other ones there are.

 Mentor P: 39,648 Keep in mind that all the voltages you are talking about are AC voltages. So to get 240Vrms from the two Hot 120Vrms lines that go into houses, the two AC voltage waveforms are 180 degrees out of phase. And for some of the other voltages that you are mentioning like 208, those are from 3-phase power distribution systems. Here are a couple hits from a google search I did just now on something like tutorial ac mains voltages 208 220 240: http://www.elect-spec.com/variac_4.htm -- Single & 3-phase power converters http://www.repairfaq.org/sam/pwrfaq.htm -- Some info on house power
Mentor
P: 39,648
As triden indicated, start with the subject "electricity" at howstuffworks.com, and go through a few pages until you get to how the electrical utility grid works (from generation to homes). Pretty good long tutorial, including 3-phase issues, starting about here:

http://science.howstuffworks.com/power.htm
HW Helper
P: 1,572
 Quote by SPL Tech Obviously that’s not how its done in houses because you can not really series two positively charged lines.
Actually, you can think of it this way.
The transformer has 2 120v windings hooked in series for a total of 240v.
The connection between the windings, in this case is called the neutral, elsewhere it might be called a centertap.
Any other ways commonly used to describe this are largely a matter of semantics.
As a practical mater, you can open the transformer, cut the link between the windings and have two independent 120v circuits.

 Quote by SPL Tech Also I am interested in how then get those weird voltage levels, such as 230 volts and 208 volts and whatever other ones there are.
It's just differently constructed transformers.
 P: 1 If the supply voltage is single phase 240VAC plus ground, is it acceptable to use one wire of the 240VAC and the ground to obtain 120VAC supply voltage? Will this be ok or will it be breaking the electrical code? For your last question... Most houses in residential areas have 240 volt, 200 amp service that is transformed down from a very high voltage from the power company. Power companies use the high voltage for power transmission because it is more efficient. From that you are able to supply devices in your house with either 120 volts or 240 volts. The 240 volt service contains two 120 volt wires, a neutral wire and a ground. To get 240 volts to an appliance, you connect both 120 volt wires to get a 240 volt potential. To get 120 volts to say a lightbulb, you would connect a single 120 volt lead and the neutral wire (which is at ground potential).
 Sci Advisor HW Helper P: 8,961 It's worth noting that the split 120v is a north American thing, Europe uses 230V single line to run everything. The UK uses 240V, this makes it a little more dangerous and means you can't have a TV in the bathroom but you do get kettles that can make a hot cup of tea in a reasonable time.
 Sci Advisor P: 4,003 Thanks MGB. Australia uses a system much like Europe's. Maybe it is the same. There are high voltage (330 KV and lower ) lines that eventually feed street transformers. The output of those is 3 phases that are all 230 volts relative to a neutral point but 120 degrees out of phase with each other. Many houses have just one phase but, by paying extra, you can have all 3 phases brought into the house. This would be done if you had an electric oven or hot water system that needed 2 or 3 phases. So, we have 3 phases and some of the wall power outlets are on different phases to others. The voltage between phases is about 400 volts. The voltage is dangerous but the rules about who can do house wiring are strict and the installer has to be licensed. You don't get bricklayers or plumbers doing electrical work unless they have double qualifications. Electrocutions are rare because safety standards are high.
 Sci Advisor P: 4,003 This thread started in 2006, so the original poster may not be around any more. You may be able to download a service manual for your dryer from Samsung in the US and you should do this if possible. The heater would certainly use 220 volts, but there would also be a motor to turn the clothes and this would be 120 volt 60 Hz. Also, there would be a timer and control module which would be low voltage but derived from a 120 volt 60 Hz transformer. There would also be a fan to blow air through the clothes. This would also be 120 volts 60 Hz. 120 volts is not a problem, but getting it at 60 Hz could be difficult. If you need someone to rewire it for you, this could get very expensive as most electricians would not want to do this. I suppose you are in too deep now to back out and throw it in the bin, but economically, that might still be a good option. Dryers are not very expensive to buy new. Simpson Model Number: 39P400M $335  P: 4 vk6kro, Thanks for the response. The Samsung model is a 10kg dryer and would cost about$3000 in Australia. It only cost \$1200 to get it from the US. If there is any way I can us it in Australia I will. Any thoughts on how to do this?