Power Transformer 110/230V Windings Question

[LinuksGuru]

Hi!

I'm about to order custom-build toroidal transformer, and now facing choice - how to build universal 110/230V primary winding. There are 3 (not incl. 100V Japanese) standards - 110V USA, 220V Europe/Russia and 240V UK. It is possible to use:

1) 2-part 110+120V configuration (in USA only first part of primary winding will be connected), or

2) 4-part 100/120V+100/120V (in USA 2 parts of primary winding will be connected in parallel).

Which one would you recommend?

Thanks in advance.

 

[Beelzebub]

Hi LinuksGuru,

Why not use 115-115 primaries? - close enough for all regions.

BTW with two primaries, either 110-110 or 115-115, you want to connect them both in parallel for US applications - so as to prevent the primary current rating from being exceeded.

 

[cogsncogs]

Hi LinuksGuru,

The voltage standard here in the US hasn't been 110V in a long time. 120V has been the standard in the US for quite some time. I would tend to agree with Beelzebub as to using 115V primaries though the 100V Japanese standard does pose a problem. Solution: Two 120V or 115V primaries with 100V taps on each winding.

Useful info:

Electricity around the world

Why was 120V chosen as the standard voltage of homes in the US and not some other voltage?

Wayne

 

[kevinkr]

<snip>
Why was 120V chosen as the standard voltage of homes in the US and not some other voltage?

Wayne [/B]

Hi Wayne,
That link is full of incorrect information unfortunately, particularly wrt to distribution. While probably not completely accurate this is much better: http://en.wikipedia.org/wiki/Electricity_distribution#Modern_distribution_systems

 

[cogsncogs]

Thanks Kevin,

I seen those bits of inaccurate information right after I posted. Especially the part about the meter! Jeez! Glad you chimed in and the link you provided!

"All AC voltages distributed to homes actually come to the buildings at 440-480 VAC. Within the meter box at every home the 440-480 VAC is broken down to 220-240 VAC and then to 110-120 VAC for use in lighting, wall plugs, and small appliances. All major appliances like electric ranges, clothes dryer, air conditioning, water heaters use the 220 VAC."

How do they fit those big dropdown transformers inside my little meter box??? They don't, they're usually located on an utility pole. No way 480V going into homes, it's 120V-0V-120V.

Wayne