Figure 3.1-1 Logic Diagram: Directional Overcurrent Element (67) - Siemens 7SR21 Manual

7SR21 & 7SR22 Argus Description of Operation
Minimum Polarising Voltage
The 67 Minimum Voltage setting defines the minimum polarising voltage level. Where the measured polarising
voltage is below this level no directional output is given and operation of protection elements set as directional will
be inhibited. This prevents mal-operation under fuse failure/MCB tripped conditions where noise voltages can be
present.

Figure 3.1-1 Logic Diagram: Directional Overcurrent Element (67)

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