ABB RELION REX640 Technical Manual page 348

Protection and control

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Protection functions

while the fictive voltage is in use. When the voltage is below

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

• The phase angle cannot be reliably measured before the fault situation.

DPHxPDOC can be forced to the non-directional operation with the NON_DIR

input. When the NON_DIR input is active, DPHxPDOC operates as a non-directional

overcurrent protection, regardless of the

Figure 207: Operating zones at minimum magnitude levels

The DIRECTION output indicates on which operating sector the current is

measured. The value combines phase-specific directions which are available in

monitored data as DIR_A, DIR_B and DIR_C.

Level detector

The measured phase currents are compared phasewise to the set

measured value exceeds the set

of the value to the phase selection logic. If the ENA_MULT input is active, the

value setting is multiplied by the Start value Mult setting.

Start value , the level detector reports the exceeding

The protection relay does not accept the

setting if the product of these settings exceeds the

Min operate voltage

Voltage Mem time

Directional mode setting.

Start value or Start value Mult

1MRS759142 F

Start value . If the

Start value setting

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