Tag: Industrial control
-
Features of Stepper Motors & How they are applied in Industrial Control
A stepper motor is a permanent magnet or variable reluctance DC motor that has the following characteristics: It is able to rotate in both directions It can move in precise angular increments It can sustain holding torque at zero speed Can be controlled with digital circuits Stepper motor moves in accurate angular increments, known as…
-
How Servo Motors are used in Process Control
Servo motors are continuous motion mechanisms that use feedback signals to provide position and velocity control in a closed loop system. Servo motors can rotate to a given position be stopped and reversed. The angular position and speed can be precisely controlled by a servo loop, which uses feedback from the output to the input. …
-
How to Tune the PID Controller
Before we discuss how to tune the PID controller, let’s look at some basic facts about PID Controller. Basic Facts about PID Controller Many control systems use a combinational of three types of control i.e. Proportional + Integral + Derivative (PID) control. The foundation of the system is the Proportional Control, adding Integral Control provides…
-
4-20 mA Transmitters (2-wire, 3-wire and 4-wire Types)
Background of 4-20 mA Signal Transmission Initially signal transmission was dominated by pneumatics before the advent of 4-20 mA signal standard. The standard was 3-15 psi pneumatic signal where the 3 psi was the ‘live zero’ and 15 psi represented the 100 %. Any pressure below 3 psi was considered ‘dead zero’ and an alarm…
-
What is a Smart Sensor?
A smart sensor is the integration of a sensor with an analogue to digital converter (ADC), a processor and digital to analogue converter (ADC) for actuator control. A typical application of a smart sensor set up is a temperature control of a furnace as illustrated below. The electronics in the smart sensor contains all the…
-
Basic Features of Modern PID Controllers
Most modern PID controllers have the following features: Manual versus automatic mode Output tracking Setpoint tracking Alarm capabilities Process variable (PV) characterization and damping Setpoint limits Output limits PID tuning security Manual and Automatic Modes When the controller manually calculates the output values based on process variable (PV) and setpoint (SP) values overtime, it is…
-
Electromechanical Relays (EMR)
Electromechanical relay (EMR) is a device that uses an electromagnet to provide the force to close or open switch contacts i.e. it is an electrically powered switch. When the electromagnet (also called coil) is energized, it pulls down on the spring-loaded armature. Relay contacts can be described as normally open contacts (NO), which are open…
-
Switchgear Equipment
Switchgear can be defined as equipment used for controlling, regulating and switching ON and OFF power circuits. Switchgear units range from the small moulded-case unit circuit breakers in a household panel board to the huge, air break switches on 750 kV transmission lines. Switchgear equipment is generally divided into four groups, namely: Disconnect/Isolator Switches Disconnect…
-
Digital PID Controllers
Digital PID controllers have replaced most pneumatic and electronic analog controllers in industrial control applications. Digital PID controllers are preferred over the analog types because they employ microprocessors which can execute multiple functions at ago hence they bring with them many advantages in addition to their ability to network with PC workstations and other controllers…
-
P&IDs and Loop Diagrams
Process and Instrument Diagrams (P&IDs), also called Piping and Instrumentation Diagrams and Loop diagrams are construction and documentation drawings that show the flow of the process and illustrate the instrumentation control and measurement instructions, wiring and connections to the process. The sections or subsystems of the process that are usually shown are called loops. A…