THC is an intricate system, understanding how THC functions and knowing the context of what you are doing when wiring THC are paramount to doing it correctly and safely. We highly recommend reading the whole THC user guide before wiring the THC function and attempting to use THC. Click here to be taken to the THC user guide.
Many modern plasma cutters will include a CNC port that has a built-in voltage divider for plug-n-play THC operation on CNC plasma tables. This makes it convenient to hook up to a THC module without having to manually connect to the raw voltage of the plasma cutter in order to read the real-time voltage during cutting. The voltage divider port works by tapping into the raw voltage circuit inside the plasma cutter and passing this through a resistor network to create a divided voltage that is much lower than the high voltage generated during cutting. The most common voltage divider on plasma cutter CNC ports is a 50:1 divided signal output (typically this is accomplished by either a 100kΩ/2kΩ or 50kΩ/1kΩ resistor network inside the plasma cutter). For example, if the plasma cutter is generating 120V during cutting, the 50:1 voltage divider port would read 120V ÷ 50 = 2.4V across it’s two voltage divider pins. Note: The Langmuir Systems THC module is tuned specifically to operate at a voltage divided input signal of 50:1. Some plasma cutters, such as certain Hypertherm models might have internal DIP switches that need to be configured in order to output the correct 50:1 voltage signal. Please consult your plasma cutter operating manual or manufacturer if you are unsure about your voltage divider port and how to configure it properly to 50:1. If your plasma cutter does not output a 50:1 voltage divided signal, it cannot be hooked up to the Divided Voltage Input port on the VIM module (click here for wiring to Raw Plasma Voltage internally as an alternative).
Each THC kit from Langmuir Systems includes a Divided Voltage Input Pigtail Cable for easy wiring to a plasma cutter voltage divider port. This pigtail has two bare wires for affixing a plug that can be used to plug into your plasma cutters voltage divider port if it has one. Another option is to purchase a 3rd part CNC pigtail cable specific to your plasma cutter and connect the Red and Black wires from the Divided Voltage Input Pigtail Cable to the corresponding bare wires on the 3rd party cable for the voltage divider. Lastly, some plasma cutters use a screw terminal block for the CNC port hookup and the bare wires of the pigtail cable can simply be installed into this terminal block as-is. If you would like to create your own cable using the provided Divided Voltage Input Pigtail Cable, we recommend contacting your plasma cutter manufacturer to determine the part number used for for the CNC port on your cutter and also the correct pins to connect to. NEVER CONNECT THE DIVIDED VOLTAGE INPUT PIGTAIL CABLE TO RAW PLASMA TERMINALS!
There is an example pin-out chart below that includes some popular plasma cutter models.