Calculation of Electrical Relay Protection Settings

Use this Protection Relay Setting Calculator to calculate pickup current, time multiplier settings (TMS), operating time, coordination time interval (CTI), and plug setting multiplier (PSM) using fault current, CT ratio, and IEC 60255 curve parameters. Protection relays employ a wide range of configurable parameters to identify defects & trip the breaker in a controlled & selected manner. Understanding each setting facilitates proper relay coordination. TSM – Time. This technical report refers to the electrical protections of all 132kV switchgear. All calculations are based on the available documentation/ information. [pdf]