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Up Topic Welding Industry / Welding Fundamentals / Portable Power Option
- - By aevald (*****) Date 04-13-2011 04:16
Hello everyone, quite some time ago I seem to remember a thread about a doodad(s) that would provide power for grinders and such by using the stinger on you welder. As fate sometime steps in, the gentleman who is assisting with teaching duties at our school walked into the office this morning and plopped one of these things down on the desk and asked if any of us had ever seen one of these. He had gotten this new probably 10 years or so ago and had never used it. Noticed that it said that the grinder, or whatever sort of electrical item that you were powering, needed to be capable of DC operation(makes total sense), in other words use a grinder, drill, or whatever, that is capable of AC/DC operation. These were built by a company called "StingerPower" headquartered in Los Gatos, Cal. I have not been able to find out of their existence anymore, however. I have included a few pictures of the unit and it's rough schematic for use. We did hook it up and it would actually power up a Makita 7" grinder, the information with it says that it is capable of 15 amps of auxilary power from a stinger with the amperage set anywhere from 70 to 500 amps. Additionally it says that it is based on using the OCV of the welder, don't quite know how this would work with an engine drive, only used it on one of our shop welders. Best regards, Allan
Parent - - By 522029 (***) Date 04-13-2011 11:26
Allan,

Interesting.  I am curious as to why they put a fuse on the ground. Any idea?

Thanks
Griff
Parent - - By aevald (*****) Date 04-13-2011 14:39
Hello Griff, I would "assume" that it is there to possibly protect the step-up coil that is part of the unit. It is sealed so it is hard to determine what all is involved with the unit's circuitry. There is a post that you attach your stinger to, then there is the clip that attaches to whatever you have your welding ground attached to. I would guess that most welders OCV's aren't quite high enough to properly power most grinders etc. so they probably are using some sort of step-up transformer to get the voltage up to around 115/120, this would also lead me to believe that they are fusing the work lead of the unit to protect those parts to keep from burning them out when you might possibly be getting aggressive with the grinder, drill, or whatever else you might be working with. Like I say, I don't know what all is involved electrically with this unit, I do know that it operated a 7" Makita grinder pretty well. Best regards, Allan
Parent - - By 357max (***) Date 04-13-2011 17:01
aevald, to use a step up transformer one would need alternating current to work. With the three prong receptacle, the "hot" leg is the one connection from the "stinger" and the neutral is not used. To complete the circuit the earth ground is used and to protect the system; alimiting 15 amp fuse is used. Even though as stated up to 500 amps may be used from the welder. That amperage would destroy a grinder and wiring if it isn't protected. The open circuit voltage would be 70+ volts. The motor & engine generators like the SA 200s may be closer to 90 volts.
Parent - By aevald (*****) Date 04-13-2011 17:16 Edited 04-13-2011 17:49
Hello 357max, myself not being an electrician or electrical engineer, I am not savvy on how you might increase DC voltage, thank you for the lesson on transformers, I do appreciate it. Here again, I haven't used a meter on this set-up to see if it is actually using the OCV of the machine or increasing it in some way. I could certainly see that you would not wish to try in any way shape or form to supply an electrical tool with 500 amp service, O-pile of copper, aluminum, and various other materials might result. Thanks and best regards, Allan

EDIT: I did put a meter on this set-up, it may be much more basic than I first considered. The voltage at the plug is actually about 2 volts less than the value registering between the stinger and the ground. The hot and neutral blades of the 3 prong outlet register continuity, the ground prong is connected to the ground clip via a small unfused wire, the neutral blade is connected to the ground clip by a fused wire. Measured voltage on the particular machine that I had it connected to was 73.9 volts DC, the machine was a Miller MarkVIII-2.
Parent - By DaveBoyer (*****) Date 04-14-2011 04:34 Edited 04-14-2011 04:46
It has a step up coil? I doubt it, as that would ONLY work on AC. A suitable transformer to handle 15 amps would not fit in that plug anyway.

My guess is that You get actual OCV, and live with the low voltage.

Universal motors [the kind with brushes] are fairly tolerant of higher or lower voltage, but they won't make full power at low voltage.

I think You could make Your own from an extension cord, and a suitable pieces on the wire ends to clamp the stinger and ground to.

The fuse prevents China Syndrome, doesn't really matter which wire it is on.

By convention, the stinger is insulated, and the ground is not, so the stinger hooks to the shielded terminal.

I guess I should have read the rest of the thread before posting.

It may interest You to understand that amperage only flows in relation to the voltage & resistance in a simple resistive circuit. Motors are a little different because they generate back EMF as they turn, so they draw less than thier resistance would indicate when running. When starting, overloaded or stalled, they draw a LOT more than the specification plate says.

I am sure You understand that when You set the amperage on a CC welder, all You are setting is the maximum it could put out, and what actually flows depends on the load.
Parent - By 522029 (***) Date 04-15-2011 00:55 Edited 04-15-2011 00:59
Allan,

Thanks for the reply.
Griff
- By Nitesky (**) Date 04-14-2011 13:05
For most DC welding the work lead is the positve terminal.
Electricity flows from negative to positive so the ground clamp is actually the electrically hot connection.  I would fuse the ground just like they did.
In my house I connect my grinder through a 15 amp fuse to a 200 amp supply.  Not much different there.

Only thing.  No way to use a GFCI
Up Topic Welding Industry / Welding Fundamentals / Portable Power Option

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