What is PSM in relay?

[Jesse22]

In the field of electrical engineering, a relay is a relay device designed to trip a switch when an error is detected. The first protection relays were electromagnetic devices based on mobile coils in motion to guarantee abnormal operating conditions such as over current, over voltage, inverse flow, over frequency and reduced frequency.

The digital protection relays based on microprocessors now emulate the original devices, in addition to providing non-practical protection and non-mechanical monitoring with electromechanical relays.

 

[Kabelsalat]

I might know this - but since I'm not native English nor is my education, this is guessworking at best. Do you have a link to where you see this letters or the whole sentence if from a text book. Also please include device brand name and model.

 

[Harald Kapp]

PSM and TMS