Control Principle - Example 1

1. 1. A Proportional Controller is used for controlling temperature in melting process. Temperature set point is   750°C and temperature measuring tool range is 0 - 1000°C .  Proportional space is set at 15%. Pressure output range from controller is 20–100kN/m² and pressure output rises when temperature increases. If pressure output is set at 60 kN/m² for temperature set point, find
   
   
   
   
           i.   Temperature for pressure output at 20kN/m² 
   
   
   
   
   
   
   
      ^{ii.  Temperature for pressure output at 100kN/m2} 
   
   
    
   
   
   
   
   2.   In a process,a Proportional Controller is used to control the liquid level in the boiler. The level is set at 8 meters and the level range is 1 to 14 meters. Proportional band is at 20%.  The output current has a range of 5–20mA.    Determine:-
   
   
             i.    The output level when current is 5 mA.
   
   
   
   
   
   
   

        ii.    The output current at a level of 10 meters.

   
   
    
   
   
   
   
   
   
   3.   An air to open valve on the inflow controls level in a tank. When the process is at the set point the valve opening is 50%. An increase in outflow results in the valve opening increasing to a new steady state value of 80%. What is resulting offset if the controller PB is:
   
   
       i)         80% 
   
   
   
                                                                                               
       ii)       40%.
   
   
   
   
   
   
   
   4.  A temperature controller has the following characteristic curve below:
   The controller has a range of 100 ⁰C to 400 ⁰C. The set‐point is 250 ⁰C. Calculate: 
                                                                                                  
   
                i.      The controller Proportional Band 
   
   
   
                                                                                                                 
                      ii.     The controller Proportional Gain