A. Electronic based relay (Static Relay)
Process : Analogue Signal
Component : transistor, diode, integrated circuit (ic)
B. Microprocessor based relay (Digital Relay)
Process : Digital Signal
Component: microprocessor
Additional features : programmable, digital readout, data recording, interfacing comm port.
Satu lagi yang sering menjadi keraguan adalah apa pula bezanya dengan numerical relay.
C. Numerical relay (Advanced Digital Relay)
Component : microprocessor
Major differ is it use mathematical algorithm to process input signals