Hypertherm HT4001 Plasma Arc Cutting System - Manual (Page 87)

INSTALLATION
4-34
HT4001
Instruction Manual
Initial Height Sensing Connections (cont.)
Upper Limit Switch and Cable – Upper Limit Switch to IHS Module
Note: The customer must supply the upper limit switch option.
Switch specifications: +12 VDC @ 1.2 ma. Gold-type contacts preferred. Select a normally closed switch that
opens when the lever is up (when the torch fully retracts). Install the upper limit switch behind the torch lifter
as in figure 4-18.
Caution: Follow the cable installation procedure below to avoid electromagnetic
interference problems with the torch lead set.
1. Use a shielded, twisted pair of 22-24 gauge wire (stranded). Use Belden #8761.
2. At the upper limit switch, connect the common wire (black) and signal wire (clear) to the upper limit switch. Cut
the shield drain wire (uninsulated). Wrap the cut end with electrician's tape.
3. At the IHS control module, loosen the two (2) latches and open the front cover.
4. Route the cable through the strain relief to connect the cable wires to 1TB.
5. Connect the shield drain wire (uninsulated) to 1TB-10 (#S). This connects the cable shield to the HT4001 frame.
The shield drain must not touch the IHS module case.
6. Connect the common wire (black) to 1TB-11 (#4).
7. Connect the signal wire (clear) to 1TB-12 (#67).
Note: If the upper limit switch signal comes from an interface on the cutting machine, the shield
must be electrically isolated from other shields in other cables. Using a separate cable will
avoid ground-loop problems.