| Protection function |
ANSI |
| Three-phase overcurrent protection INST,DT or IDMT - I> ... I>>>> |
50/51_1..._4 |
| Residual overcurrent protection INST, DT or IDMT - I0> ... I0>>>> |
50/51N(S)_1...4 |
| Harmonic overcurrent protection / inrush blocking INST, DT or IDMT - Ixh > ... Ixh >>>> |
50/51h/68h |
| Cold load pick-up block - CLPU |
68 |
| Current unbalance / broken conductor protection INST, DT or IDMT - I2 (I/I1)>...I2 (I/I1)>>>> |
46/46R/46L |
| Low or high-impedance restricted earth-fault / cable end differential protection - I0d> |
87N |
| Motor thermal overload protection - T > |
49M |
| Motor start-up supervision / locked rotor protection - Ist> |
48, 14 |
| Frequent start supervision - N> |
66 |
| Undercurrent / loss of load protection - I< |
37 |
| Mechanical jam protection - Im> |
51m |
| CT supervision - CTS |
|
| Breaker failure protection - CBFP |
50BF/52BF |