NPS Characteristic Fault Angle
The Characteristic Fault Angle is the expected fault angle for a forward NPS overcurrent fault.
For NPS protection, the Characteristic Angle can be configured for a value between -179° and 180°.
120° is the default Characteristic Angle for NPS faults. So an NPS fault where the NPS current INPS leads the NPS voltage VNPS by 120° would be a forward fault in the centre of the forward sector.
When the Tripping Direction is forward and the Forward Sector Width is the default 90°, NPS faults with fault angles between 30° and 210° (-150°) would cause NPS Directional Protection to Arm and potentially trip.
The Angle at Fault reported in the Event Log would be 120°.
The Event Log will also record:
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Pickup NPS
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NPS Directional Armed
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NPS Protection Trip
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Angle at Fault 120°
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Polarising Voltage at Trip VNPS
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Polarising Voltage at the Maximum VNPS