Quick guides

Short answers to the questions that always come up in the panel and on the plant floor, with a simulator or a calculator to try it on the spot.

Overload relay or motor protection circuit breaker: which one?

What each one protects, how they work with the contactor and which to choose for each motor.

PNP or NPN sensor: the difference and how to tell which you have

What changes between them, how they are wired and the multimeter test.

What 4–20 mA means and why it does not start at zero

The most widely used signal in instrumentation, with a calculator to try it.

What is a contactor and what is it used for?

How it works, its terminals, how it differs from a relay and the seal-in contact.