There is a purpose. I am going to test out an imported welding machine that advertises a 60% Duty Cycle at 120 amps however there is not any literature availalble for the machine that indicates the secondary voltage. I can use a voltmeter while welding but was thinking if there was a simpler and equally accurate way or not.
The machine is listed at 85% efficient and that seem pretty good for a machine that inexpensive. If it can burn a 1/8" E7018 steady enough to weld up a pipe, I will be impressed (6" type pipe)
I know it takes so much energy to raise water 1 degree. I just wondered if the same went for steel. I am sure it does but don't know if it has been measured or verified before for an electrode.
I think the amp & voltage meter should work out fine, but to get to 60% duty cycle You have to have the arc lit for 6 minutes continuously. I guess if You change electrodes as fast as You can You will find out what You need to know.
With regards to the question about how much heat it takes to raise the temperature of a given ammount of steel 1 degree, that is called "specific heat" Water is the standard, it has a specific heat of 1.000
Will a voltmeter give an accurate reading with the variations in voltage related to arc length ? I was thinking it would take so many watts to melt so much electrode.
The voltmeter may be the way to go.
If You usean analog meter and have someone read it while You weld You should be pretty good. The analog nedle will average out extremely short duration changes, how a digital deals with that depends on the buffering in the meter. In the end, You are looking for performance between the end of the electrode and the work. You can probably experience that better than You can describe it with numbers. Run the machine hard & see if it gets ornery when it starts to get hot.
Why not just short it into a load bank and see if it smokes after seven minutes? Oops! Never Mind! You want to actually be able to use the machine after the test ;)
It is an imported inverter at a fraction of the cost of a blue, red or yellow one. If I can burn some 1/8" for 6 minutes straight and off for 4 I will be impressed. The imported says that the machines will perform as described its just that all is listed is 60% at 120 amps. 120 ams at 12 volts is still 120 amps but not much toweld with.
It comes in Monday so I will play with it some.
Well, you aren't expecting much going into it, so it just might surprise you. Good luck with it.
I am looking forward to it. Its a shame I have been welding since 80 but don't have a "real" welding machine. My little 80 amp inverter may be retired after this but it remains to be seen. The 80 amp machine has been an excellent value but of course limited.
Pipewelder
If this is just an empirical test, simple joules formula and calibrated volt and amp gauges will probably adequate. If you are doing a scientific or forensic evaluation, you would have to take into consideration many factors including ARC Physics. You should contact someone like Underwriters Testing Labs. Miller or Lincoln also have the specilized testing equipment required.
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