Japan's electrical supply

[edexlab]

I was talking today to a colleague who went to Japan to do an install and he mentioned something which he said he'd never got round to researching. ...

He said the supply there was 200 volts
3 phase ,100v 1 phase, 50 or 60 Hz depending on region in the country

Yet when he tested the supply between lines and earth he got 100v to earth on 2 phases and nothing between 3rd phase and earth,
(between phases it was 200v)

This made him suspect something was wrong so he consulted a native electrician who said this was correct?

Does anybody know how this system works????
It's just for my own curiosity really I've looked online but have yet to find anything which explains it well

 

[shanky887614]

Not true, 110/ 220 is obsolete in the US, there 120/240V, single phase, 120/240V 3 phase (some power companies are not supplying it to new customers anymore) I do not care for it because of the 208V high leg, 208Y/120V, and 480Y/277V, Canada uses 600Y/347V rather then 480Y/277V. The primary users of "110, 220" are DIY'ers, but then there are the idiots who write "110/208V'' on a panel circuit directory.

i would be suprised if there is no 110/220 still in the usa it would be very expensive to change the whole country by such a small margin

 

[Lucien Nunes]

between lines and earth he got 100v to earth on 2 phases and nothing between 3rd phase and earth,
(between phases it was 200v)

Then the three wires he measured were not three phases. Never mind whether it's corner, centre or side grounded, you cannot have two phases of a three-phase system that are 200V apart, each of which is 100V from another phase.

It must have been a split phase centre-grounded 100-0-100 V supply, like the US standard 120-0-120, and very occasionally in the UK 240-0-240. It could have been part of a 4-wire high-leg delta, where the high leg is 173V wrt earth, but that was not one of the three wires he tested.

 

[norcal]

i would be suprised if there is no 110/220 still in the usa it would be very expensive to change the whole country by such a small margin

There no 110 or 220V appliances built anymore, except for some China garbage, 120/240V has been the standard for many decades.

 

[edexlab]

Ok got a bit closer to the truth today , spoke with the original bloke and another colleague,

The second guy remembers that when this polarity test was done between phases gave 200 v
Two of the phases individually to earth gave 110 ish volts and the third was much higher ,around 170v as Lucien described ,
So thanks for everyone's input on this !
It seems the first guy was a bit confused and forgot the detail but interesting none the less!

 

[Gardner]

i cant speak for japan but in the us im guessing 4wire L1,L2,N and E

3 wire L1-N-L2. TN-C-S earthing system.

they run on 110spn 220polyphase

120/240, 110/220 has not be used in decades.

 

[shanky887614]

3 wire L1-N-L2. TN-C-S earthing system.



120/240, 110/220 has not be used in decades.

old post mate after so long you cant edit, i have been corrected in this thread months ago