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10. OPERATION (continued)
10.1.6 AC Waveform
In the case of AC TIG and AC-DC TIG welding, the following three output current waveforms
can be selected with the AC waveform selection key (
ԙ
). Use these current waveforms while
taking advantage of the respective features.
Also, the AC frequency and AC balance are stored in memory for each AC waveform.
Mode
Output current wave-form
Characteristic
STANDARD
Rectangular pulse wave-
form which peak value of
straight and reverse polarity
current are equal.
Welding operation can be carried out in
a wide range from thin to thick plates.
Also, since stable welding operation
can be performed in the whole current
area, this waveform can be utilized
most generally.
HARD
Rectangular pulse wave-
form which peak value of
straight polarity current is
different from reverse
polarity current.
Such centralized arc as in DC TIG
welding is obtained. This waveform is
effective for fillet welding of a thin plate
and for the 1
st
layer of bevel or the like.
Among these three modes, electrode
consumption is the smallest in this
mode, but an arc sound becomes
larger.
SOFT
Sine wave-form which peak
values of straight and
reverse polarity current are
equal.
Soft arc is obtained. This mode is
effective for thin plate butt welding, etc.
Also, the arc sound level is low.
Maximum welding current is 200A.
*CAUTION:
If the welding current exceeds 200A in the hard mode, the bead width is larger than the AC
balance, thus ceasing to place a favorable bead. Accordingly, the hard mode is suitable for the
case when the welding current is smaller than 200A.
10.1.7 AC Frequency
When the initial conditions, main conditions or crater filler conditions are being selected, press
the AC frequency setup key (
ԝ
), and the LED in the left upper part lights up, the set point is
displayed on the right-side digital meter, then the “Hz” LED lights up. On the left-side digital
meter, the standard value is flashing on the display. In this condition, it is possible to set up the
AC frequency in AC TIG and AC-DC TIG welding, using the parameter adjusting knob (
ԛ
). The
setup range is 50Hz to 200Hz.
By pressing the AC frequency setup key again or the parameter selection key (
Ԛ
), the system
display screen returns to the parameter item in which the parameter was adjusted to the value
of one step ago.
If the AC frequency is made high, the arc concentration will increase and if it is lowered, the arc
spread is on the increase. Also, even when AC frequency is changed, the depth of penetration
remains unchanged – constant.
In the condition that the AC waveform is “Standard” and “Soft”, the standard value for AC
frequency is 70Hz, while the standard value becomes 100Hz in “Hard”.