What you're experiencing is the nature of
the high frequency switching inverter welding
machine. They're programmed to provide a
higher voltage at 'no load' in preparation for
'striking' the arc. The initial high voltage makes
the arc easy to strike and easier to maintain
while welding.
Once the arc is 'struck' and current flows
through the arc, the welder's current control
adjustment takes over and limits arc current to
the pre-set maximum. It's all very efficient and
good for welding.
In order to decrease the 'no-load' voltage and
assure that it remains low, and adjustable, it will
be necessary to alter the 'programming' of the
controller circuit inside the welder.
I haven't been able to find the details for your
model of welder so I'm unable to say exactly
how it need be done. However, if you know of
anyone who is skilled in electronics and/or
computers, they may be able to figure it out
by studying the circuit board and the control
circuitry. It is basically just a very high power
switching power supply very much like what
is inside every computer.
It simply needs to be slightly 'modified' to
operate in Voltage Mode rather than Current
Mode. Once that is done then it'll be very useful
for you. Because it operates at a high frequency
the transformer in the welder will be much smaller
than a welding transformer which operates at
50/60 Hz., but still able to produce nearly two
hundred amperes.
If you're not able to find someone to make the
necessary 'modification' to your welder then
it would be best to find a conventional transformer.
In fact, it is very easy to re-wind the large transformers
found in the inexpensive microwave ovens. Try to
find an old microwave oven that is no longer working.
In most cases the transformer secondary winding
which produces high voltage for the magnetron will
be shorted. The primary winding will still be good.
Remove the secondary winding by cutting it away
carefully, then replacing it with a suitable number of
turns of heavy wire to obtain the lower voltage you
desire. There are instructions on how to do this on
several web sites. A re-wound microwave oven
transformer (MOT) is nearly indestructible.