Galaniz
Member
I am working with a FB 58 TCONT_CP with sample time set to 1 second P GAIN set to 10, I to .13, D to .79.
I am controlling a process heater/incinerator by varying combustion air/gas with a VFD. I am able to maintain my setpoint within 1 to 2 percent either way, but within that temp range, my VFD swings from 4-20 mA constatnly. I have tried auto tune and manual tuning and I can slow it down a little, but I am unable to get the VFD to settle. I have varied sample time and the coefficients to no avail.
The osciallating VFD would be okay, however, I am trying to maintain O2 concentration and the osciallations are making this difficult.
Any suggestions for slowing down the output to the VFD so that it could settle down to semi constant speed.
Addtional info: the PID coefficients were originally taken from an old Partlow + controller that was previously controlling the temperature and which supposedly maintained a realtively constant output speed.
Thanks.
I am controlling a process heater/incinerator by varying combustion air/gas with a VFD. I am able to maintain my setpoint within 1 to 2 percent either way, but within that temp range, my VFD swings from 4-20 mA constatnly. I have tried auto tune and manual tuning and I can slow it down a little, but I am unable to get the VFD to settle. I have varied sample time and the coefficients to no avail.
The osciallating VFD would be okay, however, I am trying to maintain O2 concentration and the osciallations are making this difficult.
Any suggestions for slowing down the output to the VFD so that it could settle down to semi constant speed.
Addtional info: the PID coefficients were originally taken from an old Partlow + controller that was previously controlling the temperature and which supposedly maintained a realtively constant output speed.
Thanks.