Magnetostrictive sensors detect the location of a magnetic ring that slides along a conductive metal tube; in other words this sensor operation utilizes the effect of a magnetic field on magnetostrictive wire to function. The figure below illustrates a Magnetostrictive … Read more
Tag: Process automation
How to Connect Discrete Sensors to PLC Inputs
Discrete Sensor Outputs
Basically sensor outputs can be categorized into two types: discrete also referred to discrete or logic and proportional also called analog. Discrete sensors supply a single logical output (1 or 0) e.g. a flow switch used … Read more
PLC Instruction Set
An Overview of PLC Instructions Types
There are various types of instructions that are available in a PLC. The instruction set will vary depending on the brand and type of processor you are working with. For example, the classic Allen-Bradley … Read more
Input & Output Modules of a PLC – Types & Applications
The input/output modules act as the signal interface between the monitoring sensors and actuators, and the controller. Additional they provide electrical isolation, if needed, to convert the input signals into an electronic format appropriate for evaluation by the … Read more
What is the Safety Instrumented Function (SIF)?
The safety instrumented function (SIF) is used to monitor a selected process parameter and takes an executive action to make the process safe, if certain limits are exceeded.
An illustration of safety instrumented function in a process plant is shown … Read more
Combustion & Temperature Control for a Direct-Fired Process Heater
The figure below shows the control schemes applied to a direct-fired process heater.
From the diagram above, the heat from the burning fuel is applied directly to the tubes carrying the … Read more
How PLC Systems are Protected from Plant Voltages
Key Requirements for Industrial Control Computers
A computer is often used as part of a control system. The input data is typically from the operator’s commands and signals from the plant (flows, pressure, temperatures, limit switches, etc.). The output data comes in form of … Read more
Steam-heated Reboiler Control System
When steam-heated reboilers are used in distillation columns and the heating medium is steam, a flow control loop for the steam will typically be incorporated. The control valve can then be placed either in the steam or condensate line. Steam … Read more
Furnace Control System for a Rapidly Changing Demand
Let’s consider the figure below:
In the system above, the output of temperature controller TC represents the process demand, and this signal is applied as one of the inputs, each to a … Read more