I06 - Process Control

What are the parameters required for control loop element ?

• Set point

• Feedback output

• Process variable

• Manipulated variable

What is feedback control ?

• do the correction based on process variable input

• To prevent error

• output variable can be a setpoint for another varibale.

• Compare process variable against setpoints

identify process model

• time integral

• dead time

• Process gain

• time contant

What is the process variable for self regulating

• Level

• Flow

• Pressure tank

• Temperature

"If opening of valve increased then PV will rise and continue to rise without reaching a new steady-state value"

Above statement refer to what ?

• feedback controller

• Non-self regulating

• controller characteristic

• process gain

Define dead time

• How much time passes before the process variable is effected by a change in the manipulated variable (MV

• How much the process variable changes when the manipulated variable (e.g. valve) is changed

• How fast the process variable responds to changes in the manipulated variable

• output / input

What is definition of process time constant ?

• How much the process variable changes when the manipulated variable (e.g. valve) is changed

• How fast the process variable responds to changes in the manipulated variable

• How much time passes before the process variable is effected by a change in the manipulated variable (MV)

• Provide insight into whether the process will be easy or difficult to control.

What is effect to dead time ?

• All the elements in the process

• The strength of controller actions whenever PV is deviate from Set point.

• Bigger heat exchangers have larger time constants than smaller heat exchangers

• Electrical signal, pneumatics, flow rates, transmitter, chemistry, heat transfer

Process model for process characteristics?

• Process Gain

• Process dead time

• process derivative

• Process time constant

Process model high order points

• 63.2%

• 23.8%

• 28.3%

• 68.3%