tig welder

tig high freq
Does anyone here know what the frequency & initial voltage is of the "high freq ac" used in TIG welders? Google's offerings seem to favor client's
advertising and "how to weld" documents, unfortunantly.
Hul
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It is not maintaining any given frequency, and is driven by arcing between lower voltage tungsten electrodes, driving a higher voltage transformer.
Volts are about 3,000 volts. Current is very small and will not kill you, it is merely unpleasant.
i
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Volts - it's about 1000V per mm (10,000V per centimetre) of elctricity jumping across a gap in air? If a TIG starter-spark will jump 10mm (which one sees? - though not good welding technique!), that's 10000V?
That follows - it takes about a million volts for electricity to jump across a metre of air...?
Is that right? (Iggy, anyone?)
Rich S
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From a sharply-pointed electrode, yes.
The breakdown voltage of air depends greatly on the shape and smoothness of the electrodes. One common rule of thumb says that it takes 30 kV to jump between 1 centimeter spheres when they're 1 centimeter apart. Smaller spheres or rough surfaces take less voltage. This is a reasonable guide when setting up high voltage electrics in a laboratory setting. Industrial designers are more conservative, for some physics experiments considerably more (10X) field strength can be got away with for small (microsecond) intervals.
hth,
bob prohaska
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yes but argon is easier to ionize.
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