All of our humidification systems function as a unified system, fully integrated and automated including a PLC controlled pump, zone humidistat/sensor and fans. The pumps are prewired to the humidistat for testing during production and ship ready to install.
So, the system functions in the following manner: a humidistat/sensor (for each zone) sends a start signal to the pump whenever humidity is required (based on the settings in the humidistat). Once the humidistat/sensor reaches the required humidity level, the start signal is terminated.
When the pump receives the start signal from the humidistat, the PLC sequentially turns on any fans that are part of the system; then the water supply to the pump, then the pump motor. The delays between these functions can be programmed to factory set timing sequences consistent with each project as require. Upon termination of the start signal, the PLC then sequentially stops the operation of the pump motor, then the valves, then the fans (if they are part of the system). The time between this sequential shut down is also programmable and can be set based on the system or project requirements.
The PLC also handles the signal from the high pressure safety switch. It will provide a delay (sufficient time to let the system fully charge). This delay also allows for a loss of pressure for a short period of time (as when a second zone is opened while the system is already running thereby temporarily dropping the output pressure) without immediately terminating the system. IF the pressure is lost beyond the set time (as when the water supply has been terminated OR there is a breech in the high pressure line resulting in a loss of high pressure in the system), the PLC will shut down the system and provide a signal to the red Pressure Fault indicator light included on the pump side panel. The PLC requires a ‘reset’ to allow the system to begin operating again.
The plc also controls a green indicator light for when the pump is operating and a yellow indicator light which illuminates after a programmed period of time – typically 500 hours – providing a notice that it is time to change the oil, check for leaks from the pump seals, check the pulley belts for wear, check the filters for possible replacement, etc…
The PLC is the brains of our pump systems and can be programmed to do whatever is needed in terms of system functionality. Although we do have a standard program, we can and do provide customized programs for clients that have specific operational requirements.
Currently, we also use the PLC to track things like the number of pressure faults, the number of on/off cycles, and the total run time of the pump.
