ABB RER620, Техническое руководство

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Section 4
Protection functions
RER620 103
Technical Manual
than Voltage Mem time or if the fault current disappears while the fictive voltage is in use.
When the voltage is below Min Trip Voltage and hysteresis and the fictive voltage is
unusable, the fault direction cannot be determined. The fictive voltage can be unusable for
two reasons:
• The fictive voltage is discarded after Voltage Mem time
• The phase angle cannot be reliably measured before the fault situation.
Figure 42: Operating zones at minimum magnitude levels
Level detector
The measured phase currents are compared phase-wise with the set Pickup value .and, if
enabled, the Pickup block value . If the measured value exceeds the set Pickup value , and
is less than the Pickup block value , the level detector reports the pickup to the phase
selection logic. If the ENA_MULT input is active, the Pickup value setting is multiplied by
the Pickup value Mult setting.
Do not set the multiplier setting Pickup value Mult higher than necessary.
If the value is too high, the function may not trip at all during an inrush
followed by a fault, no matter how severe the fault is.