Attributes . distance relay 21 || underimpedance 21G || overfluxing (V/Hz) 24 || synchro-check 25 || undervoltage 27 || positive sequence undervoltage 27P || directional active underpower 37P || field loss (underimpedance) 40 || negative sequence overcurrent 46 || thermal overload protection 49 || earth fault overcurrent 50N/51N || phase overcurrent 50/51 || breaker failure 50BF || switch ON to fault (SOTF) || capacitor bank unbalance 51C || voltage-restrained overcurrent 51V || overvoltage 59 || earth fault overvoltage 59N || restricted earth fault 64REF || stator earth fault 64S || directional phase overcurrent 67 || directional earth fault 67N || H2 detection 68H2 || H5 detection 68H5 || pole slip 78PS || underfrequency 81/81N || rate of change of frequency 81R || lockout relay 86 || machine differential 87M || programmable stages 99 || programmable curve || cold load pick-up . Names