Home » English riddles » Protection » Protection Riddle No.13 – Setting of earth fault relay » Reply To: Protection Riddle No.13 – Setting of earth fault relay Reply To: Protection Riddle No.13 – Setting of earth fault relay 2021-08-03 at 11:08 am #1337 Hamid Mr. AMIR KHASHAYAR, excuse me I think we must go back to basic conseption of electrical transformer.