Plasma-Jet® Alarm System Monitors Multiple Functions

The Corotec Plasma-Jet® Alarm System is designed to continuously monitor the operating parameters of each discharge head and is designed to provide a separate, dry-contact, alarm relay output for each head if any discharge head falls outside of normal operation.

The PJ alarm system monitors the following functions:

• Blower power

• Blower speed

• Head Select

• Output power

The PJ alarm system utilizes a separate 4-quadrant, real-time, precision analog multiplier to calculate output power for each discharge head. Output levels are then buffered, amplified, and finally sampled by an embedded microcontroller which performs an A/D conversion of this level for comparison. All other functions such as blower power, head select, and blower speed are routed through a 16-channel analog multiplexer which is addressed by the microcontoller for sampling of these parameters. The microcontroller uses proprietary software to monitor discharge head function and output level at rates of at least 1,000 samples per discharge head per second, or more, depending on the number of heads being sampled.

The alarm system is designed to function automatically in both continuous and cycling modes of operation. However, ON cycle time in cycling mode must be in excess of .75 seconds in order to allow the power level signals to properly stabilize. If the unit is cycled such that the ON time is less than about .75 seconds, the alarm system will not be able to detect output power level problems or faults.

The alarm system will produce an alarm output with a duration either 2 seconds, or for the duration of the fault, even if the fault is present for less than 2 seconds such as during cycling operation - in other words, if a fault occurs the alarm relays will close for no less than 2 seconds. This allows for proper alarm annunciation and fault sensing even during rapid ON-OFF cycling of the discharge.

The Plasma-Jet Alarm system was designed for both new equipment installation and field retro-fits. Field retro-fit installation consists of drilling holes in the cabinet, mounting the board, and basic interconnection wiring - it should be able to be accomplished by a technician, electrician, or maintenance personnel with basic wiring experience.

* * *