Why are these diagram depictions shown upsidedown (plug C anyway)? cheers Baron Carter
-----Original Message----- From: M R [mailto:[EMAIL PROTECTED]] Sent: Friday, 24 January, 2003 07:27 To: U.S. Metric Association Subject: [USMA:24592] Re: Power http://www.starkelectronic.com/fzfv.htm Most of the countries in North & South America use 110V, but all other countries use either both or only 220V. Madan --- kilopascal <[EMAIL PROTECTED]> wrote: > 2003-01-23 > > > As a note: As an Electrician I have connected one > of these 24O volt US clothes driers for some US > citizens that migrated here. I still required a > 240/120 volt step down transformer to control > aspects of the drier, such as the light inside the > drum and the motor that rotated it. (Australians in > dry climates typically use clothes lines located > outside in the Sun rather than a clothes drier.) > > I don't understand why Americans who migrated to > Australia can't buy an Australian clothes dryer. > I'm sure they must exist. To import a clothes dryer > from the states, modify it so it will work in > Australia has to be expensive. In addition what > happens when it breaks and parts are not available? > What about replacement 120 V bulbs? Or other such > parts? > > What about the cycle timer that runs at 120 V, but > designed for 60 Hz? If it is run at 50 Hz, it will > run slower, and hotter if run at 120 V. Most cheap > 50/60 Hz motors are designed for 220 V @ 50 Hz and > 240 V @ 60 Hz. Or 110/120 @ 50/60 Hz. > > I have a fully electric dryer that runs at 240 V. > The circuit feeding it is rated for 30 A. It > connects with a 3 wire plug. The third plug is the > safety ground (earth). If there is any component > inside that needs 120 v, maybe even 24 V, it is > derived internally from the supplied 240 V. There > is no need for an external or additional transformer > to supply the 120 V transformer that you mentioned > above. > > > Australian and European systems use 220 - 240 > volts at 50 hertz, and as such we can use half the > size of the conductors the USA requires to supply > the same load at 120 volts. > > The USA uses 120 volts nominal at 60 hertz for > general fixtures (eg washing machines, TVs. etc.), > and uses 240 volts nominal at 60 hertz for higher > loaded appliances (eg clothes driers and large > air-conditioners). I have been informed that while > 120 volts is safer than 240 volts in the event of an > electrocution, it can be the cause of more > electrical fires that begin due to the higher > current being drawn on faulty conductors or joints. > > > Electric stoves also run on 240 V. Some heavy > duty tools, such as some air compressors may require > 240 V to operate. > > > The air-conditioner in my home is rated at 240 > volts and 15 amps at a power factor of 0.7. This is > the maximum sized unit allowed in Australia on a > single phase. Larger units must be connected to a > three phase supply, which is due to starting > currents that can be several times higher than the > running current. Each of the phases to neutral is > 240 volts at 50 Hertz. Between any two phases is > 415 volts at 50 Hertz. > > A single phase unit in the United States is > permitted to draw up to 40 running amps. I presume > this is most likely due to the complexity involved > in the supply of three phases to the suburban home. > > The American system of using a centre tapped > transformer, and grounding the centre tap is known > as the Edison system. I guess Thomas Edison must > have devised it. It was devised in a time when > copper was abundant and cheap and people thought the > extra cost of the of having larger conductors was > better than the chance of being electrocuted with > higher voltages. > > The European standard was chosen because cost was > considered more important. The Europeans put a > greater effort in designing plugs and sockets that > were shock resistant. That is by the time the > contacts of the plug are exposed to possible contact > with fingers, the pins are no longer touching > anything live. Even light sockets are designed so > that by the time the bulb thread is exposed it is no > longer in contact with the socket contacts. Thus if > someone came in contact with the contact while > changing a bulb, the person would not be shocked. > > The European system was designed to also save > money by not employing a transformer to derive > single phase from 3 phase. This way 3 phase can > economically be brought into the home. Motor and > heating devices that run more efficiently at 380 - > 415 V can be connected across the line in delta if > no neutral is needed, and in Wye, if the neutral is > needed. Single phase 220 - 240 V can be derived > from a line to centre tap (neutral) connection. > Similar to a Wye. > > In the US industrial voltage (3 phase) is almost > always 480 V. 240 and 208 V are used seldom. 208 > V, mostly for lighting. 480 V line to neutral > voltage is 277 V (480/3^-2, which there is nothing > made to run at this voltage. We don't use 415 V for > anything, so we can not use the European system to > get 240 V line to Neutral. If we want 240 V, we > have to transformer it from 480 V. A cost item. > > In some plants, lighting is balanced around a 3 > phase 208 V system. The lights are all 120 V and > are connected line to neutral. Doing it this way, > you can connect more lights economically then on a > two wire or even a three wire system. > > Because of the Edison system in use, it is not > economical to bring 3 phase into the home. In order > for each home to have both a 3 phase and single > phase system using 480 V (or even 240 V) and 120 V a > costly transformer(s) would be needed in each home > to provide both forms of power. so, we are stuck > with what we got. > > I remember when I was in Korea in the early 90s. > They were switching everything from the 3 wire > American inspired Edison system to the European > system. All the plugs were changed from the two > flat pin type to the Schucko type used in Europe. > There reason was better economy at 240 V. They did > however keep the 60 Hz frequency. > > John > > __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com
