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. Coordinating overcurrent relays across multiple protection zones is one of the most consequential tasks in power system design — get it wrong and a single downstream fault trips an entire substation. They should not be installed purely as a means of protecting systems against overloads. The relay settings that are selected are often a compromise in order to cope with both overload and. This technical report refers to the electrical protections of all 132kV switchgear. All calculations are based on the available documentation/ information.
