ABB REC650 - Calculating Settings for Four Step Phase Overcurrent Protection

IEC09000451 V1 EN
Figure 7: Inverse time operation characteristics for selectivity
3.1.5 Calculating settings for four step phase overcurrent protection
3-phase output, LV-side OC4PTOC (51_67)
The 22 kV phase overcurrent protection has the following purpose:
• Main protection for short circuits on 22 kV busbar
• Backup protection for short circuits on outgoing 22 kV feeders (if possible)
The reach of the phase overcurrent line protection is dependent on the operation state and
the fault type. Therefore the setting must be based on fault calculations made for different
Section 3 1MRK 511 286-UUS A
REC650 setting examples
46
Application manual