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Copy edited (e.g. ref. <https://en.wikipedia.org/wiki/Volt> and <<http://english.stackexchange.com/questions/15953>>).
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edit approved Jul 8, 2016 at 16:35
Peter Mortensen
edit approved Jul 8, 2016 at 16:35
Peter Mortensen
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This is so that in 110v110 V land, you connect the primaries in parallel, and in 230v230 V land you connect them in series. In each case, each primary winding takes about the same current, so the same heating and same transformer action.

One problem with this setup is that if you connect the 110v110 V configuration to a 230v230 V supply, you get smoke.

Modern laptop power supplies with a 'universal' voltage input from 90 V to 260v260 V work in a completely different way, without using a mains input transformer like this.

This is so that in 110v land, you connect the primaries in parallel, and in 230v land you connect them in series. In each case, each primary winding takes about the same current, so same heating and same transformer action.

One problem with this setup is that if you connect the 110v configuration to a 230v supply, you get smoke.

Modern laptop power supplies with a 'universal' voltage input from 90 to 260v work in a completely different way, without using a mains input transformer like this.

This is so that in 110 V land, you connect the primaries in parallel, and in 230 V land you connect them in series. In each case, each primary winding takes about the same current, so the same heating and same transformer action.

One problem with this setup is that if you connect the 110 V configuration to a 230 V supply, you get smoke.

Modern laptop power supplies with a 'universal' voltage input from 90 V to 260 V work in a completely different way, without using a mains input transformer like this.

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Neil_UK
Neil_UK
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This is so that in 110v land, you connect the primaries in parallel, and in 230v land you connect them in series. In each case, each primary winding takes about the same current, so same heating and same transformer action.

One problem with this setup is that if you connect the 110v configuration to a 230v supply, you get smoke.

Modern laptop power supplies with a 'universal' voltage input from 90 to 260v work in a completely different way, without using a mains input transformer like this.