VOLTAGE
BASED PLASMA TORCH HEIGHT CONTROL
An arc voltage
based height control measures the DC voltage between the Torch head in your
plasma and the work plate you are cutting. The Torch is negative (-) and work plate
is positive (+). It is actually measuring the voltage that is created by the
resistance of the plasma arc.
Voltage Controlled THC
has a voltage setting that is controlled by the
machine operator. This is the reference voltage that the height control will try
to keep.
If the Torch
moves UP position the Arc Voltage increase and when the Torch move DOWN or
getting closer to the work plate the Arc Voltage decreases.
During
cutting process if the operator
sets 120 volts on the height control and the actual voltage that the Voltage Controlled
THC
measures between the electrode and plate is 140 volts the Voltage Controlled THC control the Z
axis drive motor to move the torch closer to the work plate till the voltage of
120 volts is achieved.
So, the
arc voltage based height control compares the SET voltage to the actual Arc
Voltage .
So far so
good, but:
1.
When the cutting speed is reduced, the plasma torch burns a wider kerf,
consequences the Arc Voltage increase and Voltage Controlled
THC makes the torch move closer to
the work plate. DIVING OCCURS.
2.
When the cutting machine de-accelerates for sharp corners or small parts this is
the same as the reduced speed. The torch will DIVE. Some plasma machine
controllers have a Voltage Controlled
THC disable function that "freezes" the torch
height, as you guess, CRASH occurs !
3. If
parts are nested too closely, or you are cutting on the edge of the plate, the
Arc Voltage will be too high and the torch will DIVE
5. A
poor ground clamp connection between the plasma and the work plate will cause
the torch to DIVE. Dirty, oxidized slats, loose connections, of plate
will all cause this issue.
6.
Moisture or other contamination in your air supply will cause height to
fluctuate as these change the resistance of the arc.
7. Air
pressure fluctuation during the cut will cause the height to fluctuate.
8. The
electrode and nozzle wear will cause the torch to get closer to the plate.
If you use Voltage Controlled
THC only, it is not adequate for
cutting quality, nozzle and electrode life.
Capacitive Sensor protect your TORCH
and allows high cutting quality
IMPROPER
HEIGHT ADJUSTMENT CAUSES

 
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