Detail 7SG14 Transformer Protection Siemens
High Impedance Restricted Earth Fault per winding ( 87REF) Circuit Breaker Fail per winding ( 50BF) Instantaneous / definite time overcurrent phase fault and derived earth fault per winding ( 50 and 50N) Inverse definite minimum time phase fault and derived earth fault per winding ( 51 and 51N) Instantaneous/ definite time measured earth fault per winding ( 50G) Inverse definite minimum time measured earth fault per winding ( 51G) Overexcitation protection Volts/ frequency ( 2 x DTL + 1 x IDMTL) ( 24) Transformer thermal overload ( 49) 4-stage under/ overvoltage( 27/ 59) 4-stage under/ overfrequency ( 81) 2-stage NPS overcurrent ( 46)
