Protection Functions
PRS-7367 47
The phase overcurrent protection can also be used in closed ring systems as short circuit
protection. This can be done in the closed ring networks and radial networks with the generation
connected to the remote end in the system thus giving fault current infeed in reverse direction.
Directional overcurrent IEDs are also used to have a selective protection scheme. In ring
connected supply feeders between substations or feeders with two feeding sources, 67P is also
used.
3.3.4 67P Settings
In the following table, i is the protection stage number, it can be set according to the requirements.
Table 3.3-3 67P settings
Setting of blocking voltage
Setting of Negative voltage
Operation setting of Negative
voltage Enable/Disable
Stage 1 Directional mode:0~2 for
"Non-directional", "Forward" or
"Reverse"
The Stage i Start current value
The Stage i Characteristic angle
The Stage i Multiplier for scaling
the start current value
0 Definite time
1 IEC Normal inverse
2 IEC Very inverse
3 IEC Extremely inverse
4 IEC Long-time inverse
5 Programmable user-defined
The Stage i Curve parameter A
The Stage i Curve parameter B
The Stage i Curve parameter C
The Stage i Curve parameter P
The Stage i Curve parameter k
The Stage i minimum operating
time
The Stage i Reset time delay
The Stage i Protection
enable/disable
The Stage i Voltage setting
enable/disable
The Stage i Alarm Enable/Disable
The Stage i Number of phases
required for operate activation