dimanche 13 août 2017

120 V or 240 V Mains - which voltage is better?

Just something I have been wondering about recently.

Most appliances can just as easily be designed for 120V mains as 240V mains so it is six of one and half of the other. More heavy duty appliances will require a higher voltage and sometimes, only three-phase will do (for example, I used to have a three phase motor to pump bore water).

Most places in the world have a 240V mains. The local power lines carry that voltage on 3 lines (plus one for neutral) and it is only necessary to tap into the line to supply the house with either single phase or three phase electricity.

America, Canada, Japan and a few other countries use a 120V mains. There the setup seems a little more complicated. As I understand it, the local power lines carry 7,200V and pole top (or underground) transformers convert it to a "center tapped" 240V supply (http://ift.tt/2wFSO1N). Each transformer supplies a single house with two phase 120V electricity (although residential complexes may share a transformer). Heavy duty appliances like washing machines can easily be accommodated with 240V but if a household needs a three phase supply then I guess they need an extra pole top transformer.

About the only advantage I can see of a 120V system is that local power lines can be thinner since they carry less current. I know an electrician who has worked in both Australia and the USA. He describes US household wiring as a "mess" and much prefers Australia's 240V system.

I was wondering if anybody involved in power distribution would like to weigh in.

via International Skeptics Forum http://ift.tt/2vuiFLz

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