USA 220V in Ireland

tails_naf · 10-08-2011 10:27pm #1

I returned home after living in the US in 2008 (great timing I know...).
I brought with me a whirl-pool bath that could use 110V or 220V in the US.
I only recently went to try it out here - and found something which has me stumped.

Aside from the 50hz/60hz thing, which should be ok, it seems the USA do 220V differently.

Here, is it 1 live, and 1 neutral, live swings 230V around the neutral.

In the US, they have 2 lives and 1 neutral, the 2 lives swing in opposite phase around the neutral, which ensures there is never more than 110V from the neutral, but up to 220v between the live-pair.
In this system, the neutral is sometimes actually done away with, and they sometimes use 2 lives and a ground for fault protection.

So this begs the question - is there any way to connect this baby to the Irish 230V system?

Does anyone know how such a system would operate?

Thanks in advance!!

[Deleted User] · 10-08-2011 10:29pm

Sounds like three-phase AC, though I'm not really knowledgeable with these sort of things. I'll let someone more experienced have a go!

M cebee · 10-08-2011 11:01pm

it should work fine -i'd say

as you say the usa 230v is split-phase(115-0-115)

with 2 hot wires

230v here is one phase and 1 'hot wire'

edit:usa is 120v/240v

tails_naf · 10-08-2011 11:01pm

Yep, That seems to be it M ceebe.

Do you think there is any possibility these can be made compatible?
I was thinking a center tap transformer could convert one to the other, but there doesn't seem to be any (that I could find) that do this job - they all seem to be 220 -> 110, single phase - no split phase.

I was wondering how different the motor/etc could really be in the end - instead of the live/neutral connected to the motor, are they in effect connecting the two phases to the motor L1/L2? Effectively the motor sees 240V differential in both cases....

tails_naf · 10-08-2011 11:36pm

When it is configured in 110V mode, it draws 16 amps (well thats the max rated current), so 1.8kW.
when it is configured in 220V mode, it draws 40 amps(!) again that is the max rated current, but it may not actually reach this.

It has a 5.5kw heater + motor, so it can draw a fair bit.

I mostly want to avoid having a transformer, as one that large will be v. costly, and will draw a fair bit of power, even when the 'load' is off. If I can run directly from the 230V we have, then happy days.

This is the install manual:
http://www.hotwatercontrols.com/PDF/85-0100-B.pdf

This 'wiring diagram' doesn't give a whole lot away..
http://www.hotwatercontrols.com/pdfs/wd-6706%20Rev.02.pdf

Maybe you can decipher a bit more from these than I did..

M cebee · 11-08-2011 10:31am

it won't work here on 230v 1 phase

the appliance needs the 2 hot legs,neutral and ground for 240v operation

you'd need a 1:1 trafo with centre tap

for 120v operation just a step-down trafo needed

DublinDilbert · 11-08-2011 11:20am

It "might" be possible if you had a wiring diagrams of the internals of the unit and someone with the right skills. It would need someone who know's what they are doing to see if it can be converted. I've done this before, for industrial automation equipment.

Looking at the wiring diagram the first problem is that the LV trafo is only a 110V, so there's the first problem. The second problem would be that there appears to only be 1 heating element, I would of imagined this would of had 2 heating elements one per phase, which would be configured/paralleled if run off single phase 110V. The PCB would need to be looked at to see where the neutral is being used on it (and what would happen if L1/L2 were exposed to 220V). Someone would also need to evaluate all of the accessories to see if they could run of 220V.

Your basically having to redesign the internals, most if not all electricians wouldn't touch this.

tails_naf · 11-08-2011 9:54pm

DublinDilbert wrote: »

It "might" be possible if you had a wiring diagrams of the internals of the unit and someone with the right skills. It would need someone who know's what they are doing to see if it can be converted. I've done this before, for industrial automation equipment.

Looking at the wiring diagram the first problem is that the LV trafo is only a 110V, so there's the first problem. The second problem would be that there appears to only be 1 heating element, I would of imagined this would of had 2 heating elements one per phase, which would be configured/paralleled if run off single phase 110V. The PCB would need to be looked at to see where the neutral is being used on it (and what would happen if L1/L2 were exposed to 220V). Someone would also need to evaluate all of the accessories to see if they could run of 220V.

Your basically having to redesign the internals, most if not all electricians wouldn't touch this.

Thanks for this - very interesting - even for that wiring diagram, which leaves all the PCB info out, you managed to see the problem with the internal transformer. From what I can see, it seems to be taking the 120V (1 phase of it) in on 2 separate windings, and outputting R, Bl and Y.
Any guess as to what these voltages might be? It seems then this Bl and the original (i.e. pre trafo) B are used to power the heater. (from the other doc B is black, and bl is blue, which is L1 and L2.

This makes some sense, as when you don't use L2, you are supposed to connect it to neutral - so in the 110v config the heater has 110V accross it, but in 220 config, it has 220 accross it - so it must be designed as a single element that can handle either voltage.

It also seems that some of the plugs (on the right hand side) only have B and w, so are 110V only - the two pump sockets at the top though seem to be 240V, but taken in B R W, so whatever the trafo that generates the R and Y voltages seems to be key here....Any ideas?

I had an idea for trying to make the irish 220 look like the us system -

connect Irish neutral to L2, and irish live to L1. Then to generate the US neutral, I could use a 2:1 trafo, with the input windings on irish L and N, and the output winding shorted back to L, with the other output winding being the us neutral.

The idea is that the trafo will generate a 110V signal from the irish 220V. Connecting one output to the irish L, means the other output will be 110V with respect to the L - i.e. just as the US neutral would be. This only works in a differential sense, it neutral would be oscillating too (I think), unlink the US neutral which would be fixed. I think this should work, but only if the case is no powered unit has a connection between the us N and L2 (as there is no gaurantee that there would be always <110v between these two).

This is pretty difficult to describe - but hope it makes some sense!

M cebee · 12-08-2011 11:41pm

they use the 1:1 trafos with centre tapped secondary's on 'safe supply units'
for labs etc

there's also a current limiting resistor on the secondary centre tap

limits voltage to earth and fault current(to about 5 or 10ma)

Dardania · 13-08-2011 9:08am

have you considered asking the manufacturer? You could be surprised - they may have assisted someone convert one to the work in europe before...

USA 220V in Ireland

Comments