Definite time relays, grading time – delta t DT = 2. Ie +Ir + Icb + Im Inverse Time Relays , Delta t IDMT = t1 ((1+E1/100)/(1-E2/100) – 1 ) =Ir + Icb + Im Dear Hamid, Please explain these Equations.
Reply To: Protection Riddle No.98 – Grading time of numerical relays protection