220v to 110v transformer

[FlevasGR]

Sup guys, today i just bought a transformer for my Hakko FX-888D which converts 220VAC to 110VAC. The hakko manual says that it needs 120V however the transformer outputs 110V and i capable of providing 100W. Is there any problem with this 10V difference?

Here is an image of the unit:



You guys having more experience than me how does it look? Is that how a trsnformer should look like? 

[corrado33]

There's no problem with the 10V difference between the output of the transformer and what the haxxo "wants."

Anything that's passed any sort of certification will be able to run on anything around 110V (barring some electric motors), as that's the voltage most of us have in our outlets (in the US.) It all depends on how far you are from the circuit breaker and whether or not you're using one leg from 3 phase power or not.

In other words, you'll be fine.

[Rufus]

The mains in Greece is nominally 230v anyway isn't it?

[FlevasGR]

The mains in Greece is nominally 230v anyway isn't it?

Yes. It ranges from 220 to 240

[Zero999]

The transformer's case should be earthed of course and it's good idea to check the continuity to be sure.

The frequency is also slightly lower in Europe and the lower voltage will make it easier on the Hakko's transformer.

[FlevasGR]

The transformer's case should be earthed of course.

The frequency is also slightly lower in Europe and the lower voltage will make it easier on the Hakko's transformer.

How can i earth the case?

The transformer has this crapy plug

[corrado33]

The transformer's case should be earthed of course.

The frequency is also slightly lower in Europe and the lower voltage will make it easier on the Hakko's transformer.

How can i earth the case?

The transformer has this crapy plug

Physically? Take a wire, attach it with a nice star washer to the case, then attach it to a long metal pole and hammer the pole into the ground. Then it has been "earthed." 

Alternatively, (If and only if you know what you are doing.) connect it to the earth wire in your walls... (carefully.) (However, I do not know if where you are HAS earth wires in the house wiring.)

[FlevasGR]

Is there any problem if i live it like that? Since i will have only the Hakko on what can go wrong?

[Zero999]

It's nothing to do with the Hakko. The problem is the transformer could develop a fault and its case could become connected to the phase conductor.

The correct solution is to change to a three core cable and three pin plug.

[Tinkerer]

Is there any problem if i live it like that? Since i will have only the Hakko on what can go wrong?

Oh boy, now ya done it. You just asked the infamous question.

On a more serious note if you dont ground the case you can get a build up of charge, which can then discharge upon someone touching it.

As said directly above me while I was typing this.

[FlevasGR]

Every wall socket on my house has an earth connection. If i do what corrado33 said with the 3 core wire and then attach the ground wire on the case would be okay? I was thinking to buy a big project box and a US wall socket and connect them all together.

[FlevasGR]

Every wall socket on my house has an earth connection. If i do what corrado33 said with the 3 core wire and then attach the ground wire on the case would be okay? I was thinking to buy a big project box and a US wall socket and connect them all together.

This is what i'm talking about:

[SeanB]

Just be careful in that the transformer will have one output connected to the one line lead, so the output could be 110VAC with the one lead connected to neutral, or 110VAC with the one side riding on 220VAC.

[corrado33]

It's nothing to do with the Hakko. The problem is the transformer could develop a fault and its case could become connected to the phase conductor.

The correct solution is to change to a three core cable and three pin plug.

Yes, this is the correct solution. While what you have above would work fine, the correct way to do it is to switch both the input and output 2 core wires to 3 core wires and connect the earth ground (of both input and output) to the case on the inside of the device with a star washer. It would also be the cleanest in my opinion.

[FlevasGR]

It's nothing to do with the Hakko. The problem is the transformer could develop a fault and its case could become connected to the phase conductor.

The correct solution is to change to a three core cable and three pin plug.

Yes, this is the correct solution. While what you have above would work fine, the correct way to do it is to switch both the input and output 2 core wires to 3 core wires and connect the earth ground (of both input and output) to the case on the inside of the device with a star washer. It would also be the cleanest in my opinion.

This is what i want to do. I just seperated the wires on the "DaveCAD" to make it easier to see. I hope nothing explodes...

[Zero999]

Just be careful in that the transformer will have one output connected to the one line lead, so the output could be 110VAC with the one lead connected to neutral, or 110VAC with the one side riding on 220VAC.

That will only be the case if it's an autotransformer. It's quite likely though it's an isolation transformer. This is easy to test by checking the continuity between the primary and secondary.: if it's an isolation transformer, it'll be open circuit.

[SeanB]

The one shown is an autotransformer, there are 2 varieties I have met. the first is a 220v winding with a centre tap, and the other is a 55VAC, 110VAC,55VAc winding variant. The first will either have the one side at neutral or line voltage and the other wire 110V offset from that, the second will always have 55VAC on one leg and the other at 165VAC, giving 110VVAC between them.

[FlevasGR]

I'm confused now  With a short answer can i do what i described or i will burn my house down?

[corrado33]

I'm confused now  With a short answer can i do what i described or i will burn my house down?

Yes. What you have should work fine. In fact most newer versions of what you have are probably wired like you have. They were just discussing the possible differences of what's inside the transformer.

[Zero999]

The one shown is an autotransformer, there are 2 varieties I have met. the first is a 220v winding with a centre tap, and the other is a 55VAC, 110VAC,55VAc winding variant. The first will either have the one side at neutral or line voltage and the other wire 110V offset from that, the second will always have 55VAC on one leg and the other at 165VAC, giving 110VVAC between them.

How do you know the one shown is an auto transformer? Do you have x-ray spectacles or something?

It's more likely it's an isolation transformer, especially given its size which is quite large for an autotransformer, which would be half the size for the same power rating and the fact the connections to the primary and secondary are on opposite ends of the case.

I'm confused now  With a short answer can i do what i described or i will burn my house down?

What you've drawn is fine.

In addition to that, if it's an autotransformer, it's important you've got polarity of the the phase and neutral correct on the primary, otherwise the secondary will float at 220V.
An auto transformer only has one winding. The neutral should be connected to the common connection which goes straight through to the load. If the phase is connected to the common instead, the voltages on the secondary will be 220V (which should be 0V) and 330V (instead of 110V). This wouldn't blow up the soldering iron but it would put extra strain on the insulation and could pose a shock risk if something goes wrong inside the iron.



On the other hand, if it's an isolation transformer it will have two separate windings, so polarity of the connections is not critical.


It should be obvious whether you've got an isolation transformer or an autotransformer when the cover is removed. An autotransformer will only have three connections to the windings. An isolation transformer will have four connections: two for the primary and two for the secondary. This is assuming of course there aren't any other taps or windings for different voltages.

[FlevasGR]

Since it has this plug which is easy to reverse the polarity each time and since its a plug and play system is there any posibility to be an autotransformer? I could mesure it to see the output voltage. I haven't done that mostly because i'm scared as hell when im probing mains

[Zero999]

There is no need to probe the mains. With the transformer unplugged, measure the resistance between the one of the pins of the US socket and the mains lead. Hopefully it'll read open circuit.

Ideally if you fit a three pin plug, you won't be able to reverse the polarity.

[FlevasGR]

I mesured the resistance. It's an open circuit but the resistance changes depending on which pin i connected the proble of the multimeter. One pin gives 0? and 6? and se second pin gives
55? and 49?

[SeanB]

It is an autotransformer with the one side of the 110V output connected to the line, and the other side of the 110V connected to the centre tap. thus depending on how you insert the plug it will either be 110VAC floating on 220VAC or 110VAC referenced to ground. Will work with the soldering station but just do not think that the output is only 110V, it is going to be as dangerous as 220V mains.

[FlevasGR]

It is an autotransformer with the one side of the 110V output connected to the line, and the other side of the 110V connected to the centre tap. thus depending on how you insert the plug it will either be 110VAC floating on 220VAC or 110VAC referenced to ground. Will work with the soldering station but just do not think that the output is only 110V, it is going to be as dangerous as 220V mains.

Ofcurse i know it's as dangerus as the 220v. So i dont have to worry in which way i will plug the station right?