Kemppi 2500 AC/DC TIG

[Mannbo]

He took them with him on his way out.

Thanks Richard

 

[Alisterdavid]

Hello everyone.
My first post here having been an avid reader for a while.
I encountered this post years ago when I was hunting for an AC tig machine... which I now have.
The machine in question is a rebranded Kemppi Mastertig 2500. Just comes in Blue and has a Tuchel 5 pin trigger socket rather than a 4 pin Amphenol.
Just to help clarify. I am an electronic and electrical engineer and have spent a significant time working with inverter technologies and switch mode power supplies. Welders are just simple versions with bigger bits inside, or smaller if you are talking about ships.

I shall split this into another post as I am on a phone. Not ideal.

1. The IEC defines the ratings standards for electric welding equipment. Any reputable machine will have a rating plate that meets this standard. As indeed the Mastertigs do.

2. The machine in question. Regardless of cooling and controls is plated as a 3 phase only machine. It will run on different voltages by pre selection of the switch under the controls. But is at all times a 3 phase machine.
UNLESS YOU ARE SERVICING IT OR UNDERSTAND HOW IT WORKS...

3. Kemppi service manual for the later (new smaller version) mastertig explains how to operate the multi voltage 3 phase machine on single phase, for testing the power circuits.

4. All inverters rectify the ac input and filter it to smooth(ish) DC. Before doing anything else in processing. This does not matter if it is single phase, DC, or polyphase input to it. It goes through a bridge rectifier and lumpy polarity correct DC comes out.

So we now know we can put almost anything into the machine where the voltage is correct. Then the power stages will get the correct level of DC they expect to "invert".

The astute amongst you will notice though that I only said the power circuit was being tested. So what about the control circuit?

 

[Alisterdavid]

Continued.
The control circuits in the Kemppi machines I could find schema for all have a separate supply tap after the input filter and main on/off switch. This supply taps from 2 of the 3 phases into the machine. Eg. Between L1 and L2.

This feed goes to a multi input transformer via the voltage selection switch behind the control panel. We therefore chose the correct tx primaries for the input voltage. There is no neutral connection involved. These circuits are independent of the power stages.
The outputs of the control tx remain unchanged regardless of what we are upto here.
Let us select 220-240 volts on the big switch.
To power the control circuits we simply need to feed the input line "pair" with 230 ish volts a.c and the control circuit will work just fine.
It does not matter if this 230 volts is derived from using 2 phases from an american 220 volt 3 phase socket or from a UK single phase live and neutral.
You still get 230 ish volts. A.c. into the control transformer and all the machine controls will work fine.. unless the machine monitors voltage on all 3 input phases - which these machines do not.

So we switch on. Having connected our L1 to live, L2 to neutral, L3 to nothing, and earth to earth(PE). And everything works as it should.
It would be fair and acceptable/safe to connect L3 to either of L1 or L2. However it is pointless. As follows.

The 3 phase input to the power stage goes through the main switch. Each contact in this switch has a rating of 20 amps (more on this in a bit). And then to a monolythic 3 phase rectifier bridge.
I if remember correctly the rectifier is rated to 25 amps per diode.

Electricity flows from our input live into the bridge, round the welder, through the work, back aging and through the bridge and up the neutral.
Whether we double up the live or neutral connection through the bridge rectifier, at some point we will be bottlenecked through only 1 diode (pair) and 1 switch contact.
We therefore have a thermal limit of 20 amps input to the welder. We will destroy parts if we continue to exceed this.
Note also the single wires are 2.5mm sq and are therefore also on the current limit.

One perfectly working 3 phase only machine on 1 phase or 2.
However remember that.

Power is drawn. Not delivered.
If you run the machine at more than 200 amps you will be reaching or exceeding the input limit of 20 amps for the components inside the machine.
A 3 phase rectified waveform has almost no ripple compared to a single phase rectified waveform. The filters are there to reduce this ripple, but are designed for 3 phase. So you could well get rough running and dropout, especially at higher currents.
There is no protection available for your now overloaded parts if you have a 32 amp supply.

So. Yes. You can have a working Mastertig 2500(w) on 220-240v 1~.
But you can not safely have a 250 amp welder.
I would work with a 10:1 current ratio based on on OCV of 25 volts:250 volt supply voltage. So 200 amps out = 20 amps in. This does not account for power factor or %eff.

Hopefully this puts the matter to bed.
Keep up the valuable source of information to welders everywhere.
I'm off to fit a 3~ EWM watercooler to my Notkemppi tig

Alister.

 

[Rsteffanel]

Ok, ok, I know its hard for some of you to understand this and I really couldn't care what Kemppi UK have to say, but come on what's so hard to understand that I am running a three phase machine on single phase (without any type of conversion setup)

I suppose you don't believe I run a three phase lathe on single phase through a VFD either! Seriously just because you (and Kemppi UK) haven't see or heard of this being done doesn't mean I'm a liar or I don't know what I'm talking about. Get a grip people and calm down, just because you don't know something and have never heard of it doesn't mean it is a figment of a person's imagination

I'm not telling people to do this, just explaining that it can and has been done and people are doing it with this machine...By the way notice that super noob said the guy selling the machine was doing it also, well there's at least two of us in the whole world doing it, but I'm sure there's more

One day when I have time I'll take a video of my machine a Kemppi 2500W (notice the W, yeah it's water-cooled and it has a Pulse panel also running on a 240 volt 50 Hertz single phase power supply and me welding with it, on second thoughts why bother, you still won't believe it I'm sure

Also they didn't make a single phase 240 volt water cooled TIG machine 15 years ago when my machine was new, so I'm not confused over what machine I've owned for the past 15 years, but anyway thanks for the help Richard!

Cheers Johnny from Australia... You know Australia, it's down the bottom of the world where single phase rules supreme and we ride kangaroos to work

Hello Johnboy303,
Can u plecase tell me how to make the conection If i want to use this ar home at 220V.Do u have a video or something?
Thank you!

 

[Alisterdavid]

Hello Johnboy303,
Can u plecase tell me how to make the conection If i want to use this ar home at 220V.Do u have a video or something?
Thank you!

Hello.

You may notice this is my 3rd post here.
I hope it helps you out.

If you want to run one of these machines. And we are ONLY talking about the mastertig 2500 (w) or it's blue clone. The bigger 3500 machine does not have voltage selection so will not operate at the lower voltages.
Why the voltage selection on a 3 phase machine. To meet global or international use and supply.
Different countries produce power at different voltages and frequency. The frequency is not a concern here as long as it is somewhere between 50 and 60 Hz.
220v 3 phase is found where the single phase supply is 110 or 120 volts. Such as the USA..
380 and 440 v is down to different phase configuration and or different generation systems elsewhere.
*****
The correct voltage range...
It must be known and pre selected with the switch behind the control panel.
It should be checked before connecting the machine to a new source.
It must not be switched while the machine is on
*******
The machine is fitted with a 4 core flex.

1 of these cores is the earth (protective earth) and should be green and yellow.
This MUST be connected to earth of the supply to ensure protection in a fault condition.

The other three wires are phase wires L1,L2, L3. the colour does not matter for this as we may not know where they are connected internally.
I do hope however that there is no BLUE wire as this can lead to a dangerous confusion caused by the change of assigned wire colours. Blue used to be a phase (live) colour, but is now assigned to neutral. This machine However has no neutral wiring.

Take a 16 amp or 32 amp single phase plug. Rated for 240 volts between pins.
Connect the earth wire to the earth pin.
Connect one phase wire to the neutral pin.
Connect the other two phase wires to the live pin.
Ensure there are no stray strands of wire to cause shorts and everything is secure.

Ensure the voltage selection is correct and you have not more than a 20 amp breaker protecting the socket you are going to use.. 16 amp if using a 16amp plug.
Connect up and switch on the welder.

If it does not power the controls up, you will need to alter the phase wire connected to the neutral pin inside the plug.
Swap the wire in the neutral pin for one of the other phase wires. And try again. This should be enough to make it work.

If you don't understand the importance of getting the wires safely and correctly terminated, or why the breaker needs to be less than 20 amps, or that there may be internal mods and a neutral added to the machine then do NOT DO THIS.
YOU CAN EASILY KILL PEOPLE/YOURSELF, CAUSE FIRE OR AT VERY LEAST DESTROY THE WELDER.

only use a single phase plug on the machine. Clearly mark the machine for single phase use only as it is setup.

If some smarta*** opens a 5 pin plug and sees the way it is wired to test the single phase theory out.. and rewires it for you, without changing the voltage switch you can kiss the welder goodbye.

If you run it at full power on single-phase you will melt the main on/off switch, the voltage selection switch, the diode bridge and possibly other components.

These machines have no input protection other than a competent installer and the correct breaker on the socket.

Good luck.

As a side note. It should also be possible by implication to run these welders on a 2 phase supply just as above. But why would you only use 2 phases. Beats me.

If this breaks forum rules suggesting a potential dangerous mod please rest assured that it is only the competence of the modifier that is the danger. As is always the case. I won't be offended if it needs deleted or redacted.

Alister.

 

[bushy]

Hello.

You may notice this is my 3rd post here.
I hope it helps you out.

If you want to run one of these machines. And we are ONLY talking about the mastertig 2500 (w) or it's blue clone. The bigger 3500 machine does not have voltage selection so will not operate at the lower voltages.
Why the voltage selection on a 3 phase machine. To meet global or international use and supply.
Different countries produce power at different voltages and frequency. The frequency is not a concern here as long as it is somewhere between 50 and 60 Hz.
220v 3 phase is found where the single phase supply is 110 or 120 volts. Such as the USA..
380 and 440 v is down to different phase configuration and or different generation systems elsewhere.
*****
The correct voltage range...
It must be known and pre selected with the switch behind the control panel.
It should be checked before connecting the machine to a new source.
It must not be switched while the machine is on
*******
The machine is fitted with a 4 core flex.

1 of these cores is the earth (protective earth) and should be green and yellow.
This MUST be connected to earth of the supply to ensure protection in a fault condition.

The other three wires are phase wires L1,L2, L3. the colour does not matter for this as we may not know where they are connected internally.
I do hope however that there is no BLUE wire as this can lead to a dangerous confusion caused by the change of assigned wire colours. Blue used to be a phase (live) colour, but is now assigned to neutral. This machine However has no neutral wiring.

Take a 16 amp or 32 amp single phase plug. Rated for 240 volts between pins.
Connect the earth wire to the earth pin.
Connect one phase wire to the neutral pin.
Connect the other two phase wires to the live pin.
Ensure there are no stray strands of wire to cause shorts and everything is secure.

Ensure the voltage selection is correct and you have not more than a 20 amp breaker protecting the socket you are going to use.. 16 amp if using a 16amp plug.
Connect up and switch on the welder.

If it does not power the controls up, you will need to alter the phase wire connected to the neutral pin inside the plug.
Swap the wire in the neutral pin for one of the other phase wires. And try again. This should be enough to make it work.

If you don't understand the importance of getting the wires safely and correctly terminated, or why the breaker needs to be less than 20 amps, or that there may be internal mods and a neutral added to the machine then do NOT DO THIS.
YOU CAN EASILY KILL PEOPLE/YOURSELF, CAUSE FIRE OR AT VERY LEAST DESTROY THE WELDER.

only use a single phase plug on the machine. Clearly mark the machine for single phase use only as it is setup.

If some smarta*** opens a 5 pin plug and sees the way it is wired to test the single phase theory out.. and rewires it for you, without changing the voltage switch you can kiss the welder goodbye.

If you run it at full power on single-phase you will melt the main on/off switch, the voltage selection switch, the diode bridge and possibly other components.

These machines have no input protection other than a competent installer and the correct breaker on the socket.

Good luck.

As a side note. It should also be possible by implication to run these welders on a 2 phase supply just as above. But why would you only use 2 phases. Beats me.

If this breaks forum rules suggesting a potential dangerous mod please rest assured that it is only the competence of the modifier that is the danger. As is always the case. I won't be offended if it needs deleted or redacted.

Alister.

Hey fella, thanks for the excellent explanation.
Much appreciated!!

I just wondered what happens when running welders from mobile generators, either plug in units or dedicated generator/welder sets.
They don't seem to ever be earthed.
Im told this is a "floating earth" the same as when there's an inverter in a vehicle to produce mains ac power.
Is this correct?
If so, what are the considerations for these systems and how do they differ from a static, grounded system?

Ta in advance!!
Nice one!