Hello, Thanks for your query. If I understood your question property, then this characteristics are derived using mathematical questions (generally inverse time equation), testing and all...It's provided bh manufacturers. Thus, when you solve the numericals, the data points always mentioned.
It's from the characteristics. Manufcature supplies the these characteristics which are derived using equations (but exact equations depends on type of relay), testing , calibration etc. The interpretation of time corresponding to PSM means that how relay reacts according to the severity of fault. If fault is more severe, relay trips quickly.
