bgtorque
Member
Hi All
I'd be interested to hear approaches hear on what options you might consider for setting up of the loop control. I'll describe the setup.
We have a test cell that has a basic air 'conditioning' setup. There is a fan with a fairly big, inefficient motor run from a PowerFlex 525. The duct work has vents from the fan into the front of the cell and a vent pulling it back out from the rear of the cell back to the fan. We also have a mixing arrangement where there is a full intake and full exhaust externally of the building.
As well as controlling the fan speed via the Powerflex (min 10Hz to max 50Hz) we have a paddle in the mixing arrangement controlled by an electro-pneumatic actuator that can block the paths to ensure that the cell is fully exhausting to the outside work and thus pulling completely fresh in from outside, or the paddle can be blocking off the outside connections to fully recirculate the air in the cell and with the benefit of the inefficient motor provide a pretty dirty, but effective cell heating capability. Obviously the paddle can opertate anywhere between these two conditions and is controlled with a 4-20mA from the PLC (the PowerFlex will be speed controlled via EtherNet connection between the PLC and PowerFlex).
In 99% of occasions we want to keep the fan speed running as slow as posible for two reasons, more economic from a power point of view and much, much quieter from a noise point of view. Thus we would tend to rely of modulating the mixing paddle accordingly. However, if we were dumping a lot of heat into the room the paddle may go to fully exhausting and then we still need to then increase the speed of the fan. However as soon as we do that then the paddle may act and start modulating. I'd be interested to hear about how you guys might set this up.
A secondary means of operation is the option to fully override the control and do max fan speed with full exhaust to evacuate the cell of any fumes in the case of a failure with then potentially shutting off the fan and moving the paddle to fully cell recirc to prevent providing oxygen in the case of a fire. These cases need to be fully defined by the appropriate risk assessment and H&S desing reviews.
Any thoughts on how you might link up these two PIDE loops for the fan motor speed and the paddle position would be gratefully received.
thanks,
-BG-
I'd be interested to hear approaches hear on what options you might consider for setting up of the loop control. I'll describe the setup.
We have a test cell that has a basic air 'conditioning' setup. There is a fan with a fairly big, inefficient motor run from a PowerFlex 525. The duct work has vents from the fan into the front of the cell and a vent pulling it back out from the rear of the cell back to the fan. We also have a mixing arrangement where there is a full intake and full exhaust externally of the building.
As well as controlling the fan speed via the Powerflex (min 10Hz to max 50Hz) we have a paddle in the mixing arrangement controlled by an electro-pneumatic actuator that can block the paths to ensure that the cell is fully exhausting to the outside work and thus pulling completely fresh in from outside, or the paddle can be blocking off the outside connections to fully recirculate the air in the cell and with the benefit of the inefficient motor provide a pretty dirty, but effective cell heating capability. Obviously the paddle can opertate anywhere between these two conditions and is controlled with a 4-20mA from the PLC (the PowerFlex will be speed controlled via EtherNet connection between the PLC and PowerFlex).
In 99% of occasions we want to keep the fan speed running as slow as posible for two reasons, more economic from a power point of view and much, much quieter from a noise point of view. Thus we would tend to rely of modulating the mixing paddle accordingly. However, if we were dumping a lot of heat into the room the paddle may go to fully exhausting and then we still need to then increase the speed of the fan. However as soon as we do that then the paddle may act and start modulating. I'd be interested to hear about how you guys might set this up.
A secondary means of operation is the option to fully override the control and do max fan speed with full exhaust to evacuate the cell of any fumes in the case of a failure with then potentially shutting off the fan and moving the paddle to fully cell recirc to prevent providing oxygen in the case of a fire. These cases need to be fully defined by the appropriate risk assessment and H&S desing reviews.
Any thoughts on how you might link up these two PIDE loops for the fan motor speed and the paddle position would be gratefully received.
thanks,
-BG-