I work for a software company that serves the utility industry. Our primary focus is relay software. The article is correct in its basic explanation of relays, but of course, they can be a little more complicated; not the principle, but its implementation.
For example there are hundreds of electric relays that service the utilities from a wide variety of manufacturers. We have GE relays as well as units from German manufacturers, and the relays run the gamut from simple electromechanical relays to microprocessor relays.
The microprocessor relays are all computer controlled and offer more settings. All relays have what’s called a nameplate where basic settings information is entered but you can also add other settings as well.
I develop software which facilitates the reporting of relay tests. These are important for government audits. If you’re a utility and your relay doesn’t work right, you can be fined millions of dollars.