Hypertherm PHC Sensor - Manual (Page 44)

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Sensor™ PHC Operation and Setup Guide
Calibration Pot Setup
ARC - Arc Voltage Calibration
This trim pot is used to calibrate the actual arc voltage used for arc voltage control feedback. To calibrate the
arc voltage, place the PHC into the arc voltage calibration mode by turning ON DIP switch #16. This causes
the actual arc voltage to display on the 3 digit LED display. The user can either perform a test cut with a meter
connected to the plasma supply output or connect a known voltage (250 Vdc max.) to the plasma interface arc
voltage terminals (negative electrode and positive ground). Adjust the arc voltage pot until the display is equal
to the applied voltage on the meter.
NOTE: For accurate operation, this procedure should be done for all new installations since the
measured arc voltage accuracy is combination of the specific plasma interface and control units.
KERF - Auto Kerf Detection Level
This adjustment pot sets the auto kerf detection level. The auto kerf function must be enabled by turning ON
the automatic kerf detect DIP switch #11. When this pot is adjusted with the PHC in calibration mode, the
display temporarily shows a 0 to 10 reference level display. The auto kerf detection works by looking for a
rapid change in the arc voltage. When the pot is adjusted toward the lower settings, the PHC looks for smaller
voltage changes and the kerf detection is more sensitive. At higher settings, the kerf detection is less sensitive.
The pot should be set sensitive enough to reliably detect kerf crossings but not so sensitive that false nuisance
trips occur and degrade the height control performance. The operation of auto kerf detect can be checked by
monitoring the yellow Hold LED on the PHC front panel during a plasma cut. If the threshold is properly set,
the yellow Hold LED lights whenever a Kerf is crossed. Note that this LED also lights when an active
Auto/Corner input is present on the CNC Interface or when the unit is set for Manual operation.
STALL - IHS Stall Sensing Level
This adjustment is used to set the Stall force sensing level during Initial Height Sense (IHS). When this pot is
adjusted with the PHC in calibration mode, the display temporarily shows a 0 to 10 reference level display.
The stall force is always used as a backup to the ohmic contact sensing in automatic mode. When it is set to
the lower settings (turn counter-clockwise), the maximum applied force is lower during IHS. Higher settings
(turn clockwise) increase the maximum applied force. If this setting is too high, the torch or consumables can
be damaged or can deflect the work piece or trip the torch breakaway. Set this adjustment as low as possible
but high enough so that false stalled plate detects do not occur in mid air. The adjustment can be checked by
executing an IHS Test with the nozzle ohmic wire disconnected.