Process Control

Cascade Control System

  Cascade In cascade control system two controllers are cascaded  to each other as shown in the diagram below.  Primary controllers output is fed to secondary controller as a Set point. Both the controllers has their own sensing elements but only secondary controller gives output to the control valve. Primary controller receives set point from …

Cascade Control System Read More »

Ratio Control

Ratio Control In Ratio Control, the controlled variable is the ratio of two measured variables. Control is effected by adjusting one of the variables –  the controlled variable, to follow in proportion to a second – the wild variable. The proportionality constant is the ratio. Ratio relays are nothing more than manually adjustable gain devices …

Ratio Control Read More »

Common Control Loops

  Common Control Loop  1.Flow   Liquid flow processes are fast,  typically 0.5 sec response or less. Gas flow is slightly slower because of the compressibility of the gas. Control components – transmitter, valve and transmission lines –  are the main dynamic elements.  The most common measuring means is the orifice plate and differential pressure …

Common Control Loops Read More »

Instruments Used In Control Loop

Instruments  I hope you have a general understanding what a feedback control loop is, if not please refer the following article – Feedback Control Loop  Sensors You have read  that a sensor monitors and measures what is happening in the process. Examples of sensors include: thermocouples, floats, limit switches, pressure switches, pressure switches, moisture meters, and …

Instruments Used In Control Loop Read More »

Basics of Feedback Control – Elements of Feedback control

Feedback Control Feed-back control is gathering information on the controlled variable and comparing it to the set point; making a decision based on that comparison; and taking action to eliminate any differences between the controlled variable and the and the set point In feedback control, there is a constant flow of information in a closed …

Basics of Feedback Control – Elements of Feedback control Read More »

Components of Pneumatic Control System

  Pneumatic Control System  What is pneumatic ? Pneumatic is the technology that makes use of gas or pressurized air. Components of Pneumatic control system 1.Directional control Valves   These are functional valves used in logic implementation. Divided according to the number of ports / passages available and number of valve positions 2.Two Way Valves …

Components of Pneumatic Control System Read More »

Scroll to Top