Dumb idea: 120v Buzz Box with 240v?

[dehved]

Trying to understand the math involved.

For the odd thick plate job, debating on trying this at half the rated duty cycle.

Specs on the princess auto buzz box are 22v out at 120v in. If powering with 240V, it would theoretically be 44v, but how many amps would depend on the rod/load i assume.

Being the TX is the same VA regardless of in and out, in theory the output would be half the amps at twice voltage, correct? Or would it be able to burn thicker rods but spatter all over the place due to the high volts?

 

[Ironman]

I would stay away from it, or any welder with a 22 OCV. You'll beat half the flux off the rod trying to strike an arc.
The output should not vary on 220, but the input should draw less amps to achieve the same watts. E over I=R says that. Basically a welder is watts in = watts out. Watts out at lower volts, higher amps equals the same wattage.
The modern IGBT transformer-less welders are Greek to me and perform magic, and I don't know how the electrical formula applies to them.

 

[slow-poke]

If I understand what your proposing (apply 240V to a transformer rated for 120V), BAD idea, the transformer core will saturate (and likely burn up)!

 

[phaxtris]

Probably going to release the magic smoke if you try what your proposing

 

[Mcgyver]

What SP said, you can't always move the voltage and still have the transformer work properly. Plus, 22V isn't going to (shouldn't) stop your heart, 44 might.

 

[BaitMaster]

You will smoke the machine. Guaranteed.

 

[Ironman]

What SP said, you can't always move the voltage and still have the transformer work properly. Plus, 22V isn't going to (shouldn't) stop your heart, 44 might.

If you look up the welder in question in Princess, it is dual voltage and he is trying to understand if the OCV will be higher with a higher input voltage. nope
A healthy human can't feel less than 47 volts. The old telephone lines were all 48 v dc.
Last week I bought a welder with an OCV of 78v. A voltage of 60V per cm across your body will cause tissue damage, though. We have all hit an electric fence in the past, they are 18-20 thousand volts and a car ignition coil will make you perk up and notice if you get in it's 50,000 volt way, but you are not dead.

 

[phaxtris]

If you look up the welder in question in Princess, it is dual voltage and he is trying to understand if the OCV will be higher with a higher input voltage. nope
A healthy human can't feel less than 47 volts. The old telephone lines were all 48 v dc.
Last week I bought a welder with an OCV of 78v. A voltage of 60V per cm across your body will cause tissue damage, though. We have all hit an electric fence in the past, they are 18-20 thousand volts and a car ignition coil will make you perk up and notice if you get in it's 50,000 volt way, but you are not dead.

How do you know what machine he is talking about ? I sure don't, I assumed it was some kind of 120v mig, stick is more like 80 ocv, 24 would make sense on the higher voltage settings of a small 120v welder

In either case doubling the input voltage on a machine not designed for multi voltage will most likely fry it

 

[Mcgyver]

all good points, but its current that kills and of course it has to go across your chest. Unlike a spark from the carpet, there's a lot of current with a welder. i thought that the number was around 24V, that above that there could be enough current through the chest to possibly cause problems?

 

[Ironman]

all good points, but its current that kills and of course it has to go across your chest. Unlike a spark from the carpet, there's a lot of current with a welder. i thought that the number was around 24V, that above that there could be enough current through the chest to possibly cause problems?

Actually it is DC that is the heart stopper, as the muscles just clench and sieze, but ac throws you off, one of the points in the Edison-Westinghouse fight. AC is safer.

 

[Upnorth]

all good points, but its current that kills and of course it has to go across your chest. Unlike a spark from the carpet, there's a lot of current with a welder. i thought that the number was around 24V, that above that there could be enough current through the chest to possibly cause problems?

It's actually more like 40 volts. I did read once where for trades anything under 50 volts is considered safe.

 

[slow-poke]

Just a little FYI. As Mcgyver pointed out it's about current flowing through the body.

Most people can't feel 1mA or 0.001A, 3mA is a mild shock and 10mA can kill you.

I = E/R

Typically when the human body is dry (high R), "tingle" voltage is somewhere in the 24-48V range, and 120V will obviously give you a very noticeable shock. So across a human the 24-48V equates to slightly above 1mA and 120V more in the order of a few mA. When wet or sweaty, shock voltage goes down while current goes up because you're now lower resistance. Resistance at the skin level is fairly high but just under the skin resistance is much lower. Some idiot killed himself with a small battery by poking the probes slightly under his skin to prove that a small battery could not shock you.

On the other hand you could connect yourself to 100,000V that is limited to 1mA and chances are you would not even be able to detect the voltage.

Current path through the body matters hand to hand and hand to opposite foot are bad because the current passes through the heart. While finger to finger on one hand would be much less dangerous.

Rubber soled shoes go a long way.

Be safe!

 

[Ironman]

How do you know what machine he is talking about ? I sure don't, I assumed it was some kind of 120v mig, stick is more like 80 ocv, 24 would make sense on the higher voltage settings of a small 120v welder
In either case doubling the input voltage on a machine not designed for multi voltage will most likely fry it

He says "Specs on the princess auto buzz box are 22v"
A buzz box is an AC transformer welder. All PA welders except one are dual voltage, and that one is a glorified battery charger, 75 amps. So we'll see what he says, I'm curious.

 

[phaxtris]

He says "Specs on the princess auto buzz box are 22v"
A buzz box is an AC transformer welder. All PA welders except one are dual voltage, and that one is a glorified battery charger, 75 amps. So we'll see what he says, I'm curious.

Not everyone calls an ac transformer a buzz box these days, a lot of guys refer to a small welder as a 'buzz' box, best not to assume he is referring to what guys used to call a buzz box

 

[dehved]

He says "Specs on the princess auto buzz box are 22v"
A buzz box is an AC transformer welder. All PA welders except one are dual voltage, and that one is a glorified battery charger, 75 amps. So we'll see what he says, I'm curious.

It's a transformer based 20 year old AC only heavy red actual buzz box. Tried it and it did work on 240, but very aggressive arc. I lost my amp clamp meter to measure actual amps coming out. Didn't try for long, but no strange noises. Curious about the saturation of the TX issue, and how to measure that. Heat?

 

[dehved]

Similar case, except no adjustment handle.

This unit found on alibaba (pictured) spec's 48v OCV !?:

Voltage 220V
Power 7.5KVA
Voltage 220V
Frequency 50HZ
Rate input capacity 7.5KVA
Output current range 60-200A
Duty cycle 10%
No-load voltage 48V
Usable electrodes 2.5-4.0
Protection class IP21S
Insulation class H
Weight 17/18kgs

Basically I'm wondering if the OEMs didn't just use the same TX in the UK and USA/CA models without altering. I looked inside and there's no 240v primary rewiring option. Just a thermal overload interrupting the cord input hot.

 

[dehved]

the other dumb idea is using 6000VA 120v-48v transformer out of an old expensive off grid low frequency power inverter, but that would need like 40A of 120v, and it can't be run on 240 or it would be 96v out.

maybe i'll just have to suck it up and buy a bigger actual 200A chinese IGBT unit.

 

[Ironman]

maybe i'll just have to suck it up and buy a bigger actual 200A chinese IGBT unit.

I did a report on this one and if I was you I would definitely suck it up. For $200 it's much better than an ac welder

 

[phaxtris]

I did a report on this one and if I was you I would definitely suck it up. For $200 it's much better than an ac welder

Even has a 30$ off coupon ATM!