welding cable reels

[Hooked_on_HP]

I am trying to come up with some ideas on building some reels for holding the welding cables on my service truck. I have about 100ft of pos. cable and 50ft of neg.Is there any way to figure out how big they need to be. I have looked at some of the professionaly built ones.but most of them are bigger and fancier than I need.
Bill

 

[alltoys]

Take measurements of fabricated ones then make your own. Also you should have the same length of cable for negative and positive cables for your machine. Unequal lengths of cable will cause stress on your welding machine.

 

[jenkinsph]

Bill,

I would hand coil the leads into the size you want and then size the bundle to determine what you need. Avoid tight bends and twisting the wire too much, that stuff is expensive now.


Steve

 

[jenkinsph]

Also you should have the same length of cable for negative and positive cables for your machine. Unequal lengths of cable will cause stress on your welding machine.

Could you explain this further?



Steve

 

[Willl]

"Unequal lengths"

Ya, never heard of that one, got any more info ?

 

[Spudland_Dave]

Take measurements of fabricated ones then make your own. Also you should have the same length of cable for negative and positive cables for your machine. Unequal lengths of cable will cause stress on your welding machine.

Dunno about that one...my brand new Miller came with "unequal length" cables...my Stinger is longer then the ground...

 

[BrentD]

From an electrical standpoint I can't see how unequal lengths would stress a welder. Yes, all wire has an inherent per-foot resistance and the longer the cables, the more power your welder has to be able to produce to get the same current at the weld. Thing is, once the arc is struck, the current is traveling down one wire and up the other making a complete circuit. I can totally understand how making the total length too long might stress the welder and heat up the cables, but I've only seen equal paths have an effect when operating at really high frequencies on things like a computers primary data bus. That's why sometimes you'll see circuit traces zigzag in apparent wasted space because they have to make the length of the trace from one side of a chip equal to the length from the other side to make sure the resistance is mostly identical across all data lines.

No idea how that would come into play in a welder.

 

[Skyco]

Unequal lengths won't matter at all. IOW 100 ft in source and 50 ft in ground would be the same as 75 ft in each. Quite a few welders are supplied with a longer source lead than ground.
Now I might be a little concerned about coiling that much wire up, as you've created an inductor (choke), and that can affect things. I'd go with as large a coil as practical, smaller with more turns will create more inductance.
I've read of people being unable to start a motor with a coiled long cord in line where the same cord layed out will start the motor fine. Total resistance is the same in either case but the inductance changes a lot. An inductor resists sudden changes in current. An old radiomans trick is to power a base station through a long tightly coiled extension cord, it suppresses lightning induced surges. Sometimes even coax cable was coiled tightly right before the equipment to suppress lightning currents on the shield.

BTW in high speed circuits the total length is important not necessarily for resistance but propagation delay. Some large mainframe computers I worked on in the late 70's had specific length cables for this reason. A signal had to arrive at the right time, not too early (short cable) or too late (long cable).

 

[BrentD]

BTW in high speed circuits the total length is important not necessarily for resistance but propagation delay. Some large mainframe computers I worked on in the late 70's had specific length cables for this reason. A signal had to arrive at the right time, not too early (short cable) or too late (long cable).

I have no idea why I wrote resistance in my previous post. I know at the time I was writing it I was trying to figure out a way to explain propagation delay in a way that would make sense to somebody that was still under the impression that electricity moves near the speed of light through a conductor and is therefore instantaneous. I guess I thought saying it was to make sure that all the data bits arrive at the connection at the same time would sound completely made up. I remember how amazed I was the first time I read about a time-domain reflectometer. (Isn't that a fun phrase to say? Spectrum Chromatograph is antoher fun phrase. )

 

[jenkinsph]

I don't think my Miller is smart enough to know the difference.


My only concern is total combined length of the leads and their wire guage.


Steve