Tweco iCNC XT - Manual (Page 31)

iCNC XT
Manual 0-5299 INSTALLATION 3-11
3.9 Voltage Divider for iHC Torch Height Control
There is a space for mounting the V-D Board located on the upper portion of an internal vertical panel near the rear of the power supply. Pre-
drilled holes for mounting the iHT V-D board as well as another popular height control are provided.
Install the Voltage Divider Board.
1. Locate the V-D Board which should be with the XT CNC.
2. Inside the Power Supply, locate and remove the mounting panel’s 2 screws and panel.
3. Install the V-D board standoffs and the V-D Board from the XT iCNC then reattach the panel with the 2 screws, securing the voltage
divider board in place.
4. Connect the wire harness 9-78XX to the green 6pin connector on the voltage divider board and screw on the CPC connector to the rear
panel hole marked “height control”.
5. The XT plasma supplies provide a terminal strip, TB4, on the right side ahead of the CCM module for connections to Arc V- (Torch);
Tip V (Pilot); Arc V + (Work). Connect wires to the voltage divider board marked Work and Electrode. Run the wires to TB4 twisting
them around each other and then connect the Work to Work and Electrode to Arc V- (Torch).
Ohmic Sense cable.
The iHC finds the plate using an electrical or resistance measurement, thus “ohmic”, contact between the conductive end of the torch and the
metal or “plate” being cut. A wire, usually a single highly flexible wire that withstands the reflective heat from the arc, is connected between the
V-D board and the torch shield cup. The XT torch includes a metal spring clip which slips into a groove in the shield cup allowing easy removal
for parts change. The Ohmic wire can be connected to this clip with a ¼” female push-on terminal.
Significant amounts of high frequency (HF) energy causing electromagnetic interference (EMI) can be conducted along this wire due to it’s
close coupling to the torch. This is the reason for mounting the V-D board away from the CCM and close to the rear panel where the Ohmic
wire does not need to pass near other sensitive electronics. It is especially recommended that the Ohmic wire not be routed near the CCM
module or along the torch leads.
Ferrite cores.
It is recommended that the Ohmic Sensing wire be wrapped through a ferrite core with several turns, at least 3 but more is better, to reduce
the energy conducted to the V-D board and into the plasma supply. The ferrite core should be located on the wire where it enters the plasma
supply. A second ferrite core added several feet (couple of meters) from the torch will further reduce the conducted EMI that may couple to
other cable/wires and cause interference.