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240v / 120v volt wiring switch
Old 17th July 2011
  #1
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240v / 120v volt wiring switch

hi,

I am building a rack mount unit, i bought a IEC connector for the mains, that has a builtin 120/240 switch on the back on it along with the fuse holder and power switch, and a torodial with 115/230 winding, wired in series or parallel accordingly.

the transformer windings I can handle, what I am confused about is how to wire the primary windings to the voltage selection switch.

the tranny has two primary windings, BLUE/WHITE and VIOLET/BROWN, I tied white and violet together to get my 230v while testing the PSU

There are four pins on the switch, I have tested with a DMM the table below shows the short (/) and open(x) corresponding to the switch position.
1&2 1&3 1&4 2&3 2&4 3&4
120 - / X X X X /
240 - X X X / / X

any ideas? + your not reponsible If i blow up!
Attached Thumbnails
240v / 120v volt wiring switch-table.jpg  
Old 17th July 2011
  #2
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Remeniz's Avatar
 

Ok.

So BLUE & WHITE is one primary winding and VIOLET & BROWN is the other 'identical' primary winding.

So wire in series for 240V and in parallel for 120V -

240VAC - Blue ------ White - Violet ------ Brown - 240VAC

120VAC - Blue/Violet ------ White/Brown - 120VAC

Use a meter to check the correct colours go with the right windings. I'll wait for others to elaborate.
Old 17th July 2011
  #3
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i think u mis-read the question. How do i wire the switch in?
Old 17th July 2011
  #4
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Remeniz's Avatar
 

Ah, my bad.

I don't see how this can be done with a 4 pin (DPST?) switch.

You need a DPDT switch, which has 6 pins and wire as per the diagram....
Attached Thumbnails
240v / 120v volt wiring switch-mains-selector-switch.jpg  
Old 17th July 2011
  #5
Use a rated switch, not a small toggle or something. Switchcraft makes a 115/240 slide switch that does this very well. It has the markings and a flat screwdriver slides it. It's good for 3 amps.
Old 17th July 2011
  #6
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Quote:
Originally Posted by Jim Williams View Post
Use a rated switch, not a small toggle or something. Switchcraft makes a 115/240 slide switch that does this very well. It has the markings and a flat screwdriver slides it. It's good for 3 amps.
its this

BULGIN|BZV03/Z0000/15|INLET, IEC, SWITCHED/FUSED | Farnell United Kingdom
Old 18th July 2011
  #7
PRH
Gear Addict
 

Are you sure that 2 and 4 are short in the 240 position?

Something doesn't add up.

If 2&3 are short and 2&4 are short, then I would expect continuity between 3 and 4 - which does not appear to be the case from your diagram.

For 115V, it looks like BL = 1, V = 2, W = 3 and 4 = BR will work.

For that assignment to work with 230V, you would need 1-2 open, 2-3 short, 3-4 open, effectively wiring the primaries in series.

I would check continuity between the output pins and each input (active and neutral) pins - that might give some better clues.

Also, have a close look on the device itself, there may be a wiring diagram embossed on the plastic housing?

Paul
Old 18th July 2011
  #8
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you are correct, 2 and 4 are NOT short in 240, I re-tested.



Quote:
Originally Posted by PRH View Post
Are you sure that 2 and 4 are short in the 240 position?

Something doesn't add up.

If 2&3 are short and 2&4 are short, then I would expect continuity between 3 and 4 - which does not appear to be the case from your diagram.

For 115V, it looks like BL = 1, V = 2, W = 3 and 4 = BR will work.

For that assignment to work with 230V, you would need 1-2 open, 2-3 short, 3-4 open, effectively wiring the primaries in series.

I would check continuity between the output pins and each input (active and neutral) pins - that might give some better clues.

Also, have a close look on the device itself, there may be a wiring diagram embossed on the plastic housing?

Paul
Old 18th July 2011
  #9
PRH
Gear Addict
 

Quote:
Originally Posted by oxide54 View Post
you are correct, 2 and 4 are NOT short in 240, I re-tested.
So it seems then that your wiring scheme will be:

BLUE = 1, VIOLET = 2, WHITE = 3 and 4 = BROWN

For 115V: Blue+Violet and White+Brown = primaries in parallel.

For 230V: Blue White+Violet Brown = primaries in series.

Double check that and see if it seems correct to you.

Paul

PS Did you need to have dual voltage capability, or it was just the transformer you happened to have?

Last edited by PRH; 18th July 2011 at 02:16 PM.. Reason: Afterthought...
Old 18th July 2011
  #10
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Quote:
Originally Posted by PRH View Post
So it seems then that your wiring scheme will be:

BLUE = 1, VIOLET = 2, WHITE = 3 and 4 = BROWN

For 115V: Blue+Violet and White+Brown = primaries in parallel.

For 230V: Blue White+Violet Brown = primaries in series.

Double check that and see if it seems correct to you.

Paul

PS Did you need to have dual voltage capability, or it was just the transformer you happened to have?
hi Paul,

thanks.

no I didn't need the dual voltage capability, but I thought I might as well use it, I bought the unit because the switch / socket / fuse are all in one unit and it savings drilling / cutting multiple size holes, and I thought as the transformer is capable I might as well implement it because, you never know the unit might end up else where and some might see the switch without checking inside the unit and use it with the other voltage.
Old 26th February 2020
  #11
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Hi,

apologies for resurrecting this but I have the exact same question with the OP and something is not clear to me.
In the selector switch diagram image above (posted by Remeniz, July 17th 2011) it is clear that for accommodating
transformer's "series" connection, wires 2 and 3 go to the middle terminals of the SW1 and that type of wiring would provide
230V to the transformer primaries.

However, it is not clear at all how those same wires (2 and 3) would accommodate a "parallel" connection of the primary transformer so to get 115V .

It's my understanding that (I'm using the wire numbers as in the selector switch diagram) for getting the transformer's primary in parallel connection, wire 1 should go together with wire 2 and wire 3 should go together with wire 4.

I don't see how that is accomplished in the selector switch diagram.

Wires 1 and 4 just connect to the far right selector switch terminals
while wires 2 and 3 just connect to the middle selector switch terminals...

Am I missing something please?
Attached Thumbnails
240v / 120v volt wiring switch-selector_switch.jpg  

Last edited by sotirisp; 26th February 2020 at 06:23 PM.. Reason: typo
Old 26th February 2020
  #12
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Radardoug's Avatar
 

The diagram is correct. Study it until you understand it.
Old 25th May 2020
  #13
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Quote:
Originally Posted by sotirisp View Post
Hi,

apologies for resurrecting this but I have the exact same question with the OP and something is not clear to me.
In the selector switch diagram image above (posted by Remeniz, July 17th 2011) it is clear that for accommodating
transformer's "series" connection, wires 2 and 3 go to the middle terminals of the SW1 and that type of wiring would provide
230V to the transformer primaries.

However, it is not clear at all how those same wires (2 and 3) would accommodate a "parallel" connection of the primary transformer so to get 115V .

It's my understanding that (I'm using the wire numbers as in the selector switch diagram) for getting the transformer's primary in parallel connection, wire 1 should go together with wire 2 and wire 3 should go together with wire 4.

I don't see how that is accomplished in the selector switch diagram.

Wires 1 and 4 just connect to the far right selector switch terminals
while wires 2 and 3 just connect to the middle selector switch terminals...

Am I missing something please?
Hi Sotiris,
The wiring is correct. Iโ€™ll explain below why.

Next the number 1, there is a โ€œdotโ€, this means that there is a โ€œconnection" there, and following that line, goes to the pin of the switch on upper right.
Next to Pin 4, same thing, but that gets connected to the pin next to it on the switch.

So, as the position of the switch is in the diagram, it is for parallel connection, where 1 & 2 are together and 3 & 4, so it is for 120V.
When you move those lines to the left (in the switch), it will join 2 & 3 only and 1 & 4 are connected anyway to AC

Now, if that is diagram is hard to understand, here is another one.

On the right as is, it is 120V, when you put it to the left, it is 240V.

I hope this helps you understand how the wiring works.

These are two ways of wiring a DPDT switch for voltage selection that I am aware of.

Whichever you select, it will work.
Attached Thumbnails
240v / 120v volt wiring switch-120_240-switch-selector.png  
๐Ÿ“ Reply
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