Found this at Plasma Spider. I think this should answer all the questions on hows and whys of the first delay is different than subsequent… and why it would be good for FireControl to use one of the available aux inputs to monitor the arc transfer signal.
There is not 2 second delay built into the Powermax65 or 85. There is a very slight (maybe 200 milisecond) delay when the torch is in postflow…as the air flow has to stop and the torch must refire…but it is nowhere near 2 seconds.
Try firing the torch with a switch (pushbutton) directly on the plasma…fire it once and then release the button…you will hear postflow…push the button again during the postflow and the torch will fire almost immediately.
If it does not fire for 2 seconds…contact me directly and I can help you troubleshoot.
Update: I was curious about the actual time difference between the original firing of a Powermax65/85 torch and when you fire it during the post cooling flow. For the original start there is a slight delay of about 100 to 200 milliseconds (varies with torch lead length) as it takes a while for pressure to build at the torch. When the start signal for the plasma is activated during post flow (cooling flow that occurs after each cut cycle for about 10 seconds), the air flow is shut off at the power supply solenoid, it takes a few milliseconds for the air pressure in the torch to drop close to zero, which allows the spring loaded electrode to contact the nozzle…then the solenoid is reactivated to start the process. Our engineers tell me that during post flow a system with 25’ torch leads takes 400 miliseconds to fire (after the start signal is active), and with a 75’ torch lead can take 900 miliseconds.
Most cnc plasma machines use the arc transferred output from the plasma (contact closure between pins 12 and 14 on the interface plug) to indicate the arc has transferred before the part program progresses beyond the plasma start command. If you are just relying on a timer between the issuing of the start signal and the start of machine motion…then there will be differences that can cause cut quality issues with most plasma systems.
Jim Colt jim.colt@hypertherm.com