Ratio Control

Hi Pals,

Is there any body tell me some links on ratio control tutorial?

Mehdi

Mehdi said:

Hi Pals,

Is there any body tell me some links on ratio control tutorial?

Mehdi

Click to expand...

I'm not sure about a tutorial. Ratio control generally is fairly straightforward. You simply want an output signal to be a multiple of an input signal. For example, a chemical dose may be a multiple of a water flow rate. You take the analog input and multiply it by a ratio to get the output. I generally find it easiest to convert the input to a percent of full scale or actual engineering units, do the calculation, and then convert the result back into the analog signal.

Example:

4-20 mA input from flow meter = 0-100 gpm
4-20 mA output from dosing pump = 0-1 gpm
Dose = 0.5% = 0.005 gallon chemical to each gallon water
input = 12 mA = 50 gpm
output = 50 * 0.005 = 0.25 gpm chemical
0.25 gpm chemical = 0.25/1 = 25% speed = 8 mA

Tom Jenkins said:

I'm not sure about a tutorial. Ratio control generally .........

Click to expand...

Hi Tom,

Thanks for your nice example.

Mehdi

Another type

http://learncontrol.com/pid/ratio.html