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Old 01-14-2017, 07:45 AM
Rufus Rufus is offline
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Default Welding cable

Hi all:
Sometime today I will be ordering 4 (four) 150 amp diodes to convert the Miller Thunderbolt over to a DC machine. I have about 10 feet of welding cable that I bought years ago and the closest I can tell it is 5/16 to 3/8 inch in diameter. Any idea as to the current handling capability this cable might have? I was hoping to A) make a reactor coil out of it and B) maybe use it to lengthen the welding leads on the machine. The cable on the machine is thicker than this cable and I noticed that my Power Arc 4000's welding cables are the same diameter as this roll of 10 feet of cable. The max that the Power Arc 4000 puts out is 125 amps AC. Any idea of current handling capability?

Thanks
Tim
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Old 01-14-2017, 07:58 AM
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Cable sizes are:
00 = .3648 is 283 amp
000 - .4096 is 328 amp

When electricity flows through a wire, it mostly flows on the surface of the wire, not through the middle. Which is why the welding cable is multi strand as well as giving it flexibility.
This is AWG standard info and for DC, but not welding cable specifically, which could carry even more. I think you will be fine with it.
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Old 01-14-2017, 09:52 AM
Lew Hartswick Lew Hartswick is offline
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Originally Posted by Ironman View Post

When electricity flows through a wire, it mostly flows on the surface of the wire, not through the middle. Which is why the welding cable is multi strand as well as giving it flexibility..
This is NOT true unless the frequency of the AC is well above any power line in the world. Skin effect does not become significant until you get above the 100s of Kilohertz. I'm not sure at what freq. it even becomes measurable but would guess it's well above 10 KHz. To top it off the skin effect would not see the individual strands anyway, it would see only the overall diameter of the cable.
...lew...
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Old 01-14-2017, 10:45 AM
Rufus Rufus is offline
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Originally Posted by Lew Hartswick View Post
This is NOT true unless the frequency of the AC is well above any power line in the world. Skin effect does not become significant until you get above the 100s of Kilohertz. I'm not sure at what freq. it even becomes measurable but would guess it's well above 10 KHz. To top it off the skin effect would not see the individual strands anyway, it would see only the overall diameter of the cable.
...lew...
This is based on Tesla's findings. If I am not mistaken, the old High Frequency Tig Welders are based on Tesla's principles. I do know that In a lot of old HF tig welders there is a spark gap in which a spark jumps across the gap and in turn fires a Hf transformer (if I am wrong, please feel free to correct me).

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Tim
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Old 01-14-2017, 07:30 PM
Oscar Oscar is offline
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Originally Posted by Rufus View Post
This is based on Tesla's findings. If I am not mistaken, the old High Frequency Tig Welders are based on Tesla's principles. I do know that In a lot of old HF tig welders there is a spark gap in which a spark jumps across the gap and in turn fires a Hf transformer (if I am wrong, please feel free to correct me).

Thanks
Tim
Exactly. High-Frequency. By definition, if you have frequency, you have an AC waveform, not Direct-current. Skin-effect only applies to very very high frequency waveforms. This is covered in any undergraduate Electromagnetic Field Theory course worth its tuition cost.

With regards to cable size and amperage, keep in mind that even though the Lincoln table shows values that take into account thermal heating, it does not take into account voltage drop, which there will always be. Be sure to use a voltage drop calculator to see if the resultant voltage drop is acceptable.
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Last edited by Oscar; 01-14-2017 at 07:39 PM. Reason: Thought the quoted text was from someone else
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Old 01-14-2017, 08:42 PM
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The old Lincoln table probably dates from the days when welding machines were capable of 30-40 arc volts at rated current. Old welders had balls.
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Old 01-15-2017, 12:23 AM
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Quote:
Originally Posted by Oscar View Post
Exactly. High-Frequency. By definition, if you have frequency, you have an AC waveform, not Direct-current. Skin-effect only applies to very very high frequency waveforms. This is covered in any undergraduate Electromagnetic Field Theory course worth its tuition cost.

With regards to cable size and amperage, keep in mind that even though the Lincoln table shows values that take into account thermal heating, it does not take into account voltage drop, which there will always be. Be sure to use a voltage drop calculator to see if the resultant voltage drop is acceptable.
+1...

I design and build bus bars and shunts that carry 45k amps or more for the EW side of copper mining. The CDA book (Copper Development Association) states that the skin effect applies only to AC current. DC current requires a minimum of cross sectional area per amp to minimize heating.
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Old 01-14-2017, 03:26 PM
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terry lingle terry lingle is offline
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Quote:
Originally Posted by Ironman View Post
Cable sizes are:
00 = .3648 is 283 amp
000 - .4096 is 328 amp

When electricity flows through a wire, it mostly flows on the surface of the wire, not through the middle. Which is why the welding cable is multi strand as well as giving it flexibility.
This is AWG standard info and for DC, but not welding cable specifically, which could carry even more. I think you will be fine with it.
Gerry that effect is called skin effect and only applies to ac current it is frequency dependent and really has little effect at the frequency's we use for power transmission and welding
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Old 01-14-2017, 07:20 PM
yooper yooper is offline
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Default Diodes

If you haven't ordered the diodes already - these are a less expensive option than four separate stud diodes and you only need one heat sink and don't have to worry about isolating / insulating the heat sinks .

http://www.ebay.com/itm/US-Ship-MDQ-...wAAOSwiO9Xi5CB
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Old 01-15-2017, 01:59 PM
Rufus Rufus is offline
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Quote:
Originally Posted by yooper View Post
If you haven't ordered the diodes already - these are a less expensive option than four separate stud diodes and you only need one heat sink and don't have to worry about isolating / insulating the heat sinks .

http://www.ebay.com/itm/US-Ship-MDQ-...wAAOSwiO9Xi5CB
I already ordered my diodes. It's amazing how someone on this website always comes up with a good alternative

Thanks
Tim
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