HTP Revolution 2500 Manual page 12

WAVE FORMS
SQUARE WAVE: The standard wave form for all modern inverter TIG welding machines. The
square wave offers excellent power, arc control, and bead appearance. A good choice, all around,
for aluminum welding. When in use, some operators may perceive the square wave sound as loud
and unpleasant. However, many operators prefer to use a square wave due to its superior
performance and features, such as the ability to run pulse.
Triangular Wave: The triangular wave form allows you to reach maximum peak current while
dramatically reducing the overall heat input. When using a triangular wave form, the machine can
be configured to show either the maximum (peak) amperage or the overall (actual) amperage
welding output on the LCD. The Amperage display (red numeric; above LCD) always shows the
max (nominal/peak) amperage. Rapid formation of melting points reduces the overall welding time,
which, in turn, alleviates distortion—especially when welding thin material. The triangular wave
creates a fast freezing puddle, which results in superior control and heat input management. Pulse
functions are unavailable in Triangular AC.
AC Balance
Balance refers to the time the arc spends above or, in the case of HTP machines, below the zero
line. What does that mean? Imagine you weld AC and you set your frequency not to 100Hz but to
1Hz (1Hz used for the purpose of easy demonstration; the frequency of the Revolution 2500 cannot
be set any lower than 20Hz). Set at 50% balance, your current would come out of the material and
go into the torch (your electrode positive (EP) part) for 0.5 seconds. For the next 0.5 seconds, your
current would come out of the torch and go into the material. Let's say you weld at 100 amps. For
0.5 seconds, you will see 100 amps come out of the material and go into the torch, and for the
following 0.5 seconds, you will see 100 amps come out of the torch and go into the material. Do
you need 0.5 seconds of electrode positive (EP)/cleaning/breaking open of the oxide layer? No,
most likely not—that is why you typically don't weld with a 50% balance. Do you want more
electrode negative (EN)/penetration and to put heat into the material you are welding (rather than
the torch)? Yes, absolutely. Most people consider an EN balance between 60 and 80% the sweet
spot. With balance set too low, the tungsten balls, and with the balance set too high, the weld bead
turns gray, flat, and dull. You may even see some peppering in the weld along with insufficient
cleaning of the oxide layer. On the Revolution 2500, you can adjust the balance from 10 to 90%.
AC Frequency
AC frequency does two things, mainly. First, AC frequency focuses the arc. Higher frequencies
feature a more focused arc and a narrower frost line, which works really well on thin material. On
thick material, higher frequencies tend to make it hard to join two pieces of material, as the focused
arc wants to cling to only one piece and not join it to the other piece. Second, AC frequency affects
heat input. As previously discussed , higher frequencies result in a lower overall heat input. Lower
frequencies result in a higher overall heat input. In other words, thin material prefers higher
frequencies (this is why the Revolution 2500 offers an adjustment range from 20 to 400Hz when
operating at an output under 100 amps), and thicker material prefers lower frequencies. Although
the adjustment above 100 amps lets you choose AC frequencies from 20 to 200Hz, at a material
thickness of 1/4", 1/2", or even higher, it is not uncommon to see frequencies of 50Hz or less be
used on a regular basis for best results.