As an electric motor’s rotor turns in close proximity to the motor windings, a bucking voltage or back electromotive force (EMF) is generated. The back EMF (BEMF) generated across the start winding is ...

Potential relays are commonly found on many smaller, single-phase, capacitor-start, capacitor-run motors in the HVACR industry. Their function is to assist in starting the electric motor. Potential ...

Programmable logic controllers (PLCs) and computer-based controllers are great for handling logic and data-collection tasks for industrial controls. But when it comes to driving motors, heaters, ...

Over the years, control relays of various types have been used by the hundreds — even thousands — to control nearly every function in commercial and industrial processes. Today, many of those ...

This chapter covers representative general-purpose relays used in the control circuits of most industrial, commercial, and consumer products. Relay names and terminology are in accordance with ...

Even the best relays can fail at some point, but what causes them to fail? Conventional wisdom lays the blame on worn-out contacts. And there is some truth to that view. Every electromechanical relay ...

No matter what the application is, when a definite-purpose solution is required, time delay relays (TDRs) can provide simple, reliable, and economical control. Adjusting the delay time is often as ...

Relays continue to be useful and popular, but in low-power, battery operated applications they tend to be power wasters. The following relay economy circuits reduce coil power significantly by simply ...

What's a designer to do when challenged with a switching application that requires handling up to 70 kV? These applications are not as rare as one may think. In fact, a broad range of applications in ...

Proper selection and effective testing can increase contact reliability in the end product while reducing the overall cost of using relays. Who said relays are pass�? While electromechanical relays ...

Last column, I wrote about various applications where fire alarm relays could be used to integrate a commercial fire alarm system with other electrical systems at a customer’s site to provide them ...