An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
Textbook
The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
Textbook
A simple control system drawn in block diagram form looks like this: Information from the measuring device…
Textbook
AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
Textbook
DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
Textbook
The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
Textbook
The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
Textbook
Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
Textbook
Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
Textbook
There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
Textbook
Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
Textbook
Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
Textbook
In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
Textbook
The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
Textbook
Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
Textbook
As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
Textbook
Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
Textbook
A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
Textbook
There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
Textbook
Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
Textbook
The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
Textbook
The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
Textbook
Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
Textbook
A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
Textbook
In order for any PID controller to be practical, it must be able to do more than just implement the PID…
Textbook
DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
Textbook
AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
Textbook
An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
Textbook
In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
Textbook
The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
Textbook
Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
Textbook
A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
Textbook
Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
Textbook
To show a practical process example, let’s examine three diagrams for a compressor control system,…
Textbook
In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
Textbook
The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
Textbook
Constructing PID control systems using discrete components is a fairly simple method involving operational…
Textbook
DC electric current signals may also be used to communicate process measurement information from transmitters…
Textbook
Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
Textbook
Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
Textbook
A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
Textbook
A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
Textbook
An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
Textbook
Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
Textbook
Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
Textbook
There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
Textbook
Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
Textbook
A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
Textbook
As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
Textbook
When control valves operate between fully open and fully shut, they serve much the same purpose in process…
Textbook
Facebook
Google
GitHub
Linkedin