ABB Relion 650 Series Technical Manual page 105

1MRK 511 424-UEN B
Bay control REC650 2.2 IEC
Technical manual
• that the product I·cos(Φ) is bigger than the set pick-up level, where Φ is angle
between the current phasor and the mta line
• that the phasor of the measured current is within the operating region (defined
by the I·cos(Φ) straight line and the relay operate angle, ROADir parameter
setting; see figure 34).
Ipickup
ROADir
Operate region
IEC05000253 V2 EN-US
Figure 35: CVGAPC, IcosPhi&U directional operating principle
where:
RCADir is 75°
ROADir is 50°
Note that it is possible to decide by a parameter setting how the directional feature
shall behave when the magnitude of the measured voltage phasor falls below the
pre-set value. User can select one of the following three options:
• Non-directional (operation allowed for low magnitude of the reference
voltage)
• Block (operation prevented for low magnitude of the reference voltage)
• Memory (memory voltage shall be used to determine direction of the current)
It shall also be noted that the memory duration is limited in the algorithm to 100
ms. After that time the current direction will be locked to the one determined
during memory time and it will re-set only if the current fails below set pickup
level or voltage goes above set voltage memory limit.
Voltage restraint/control feature
The overcurrent protection step operation can be made dependent of a measured
voltage quantity (see table 40). Practically then the pickup level of the overcurrent
step is not constant but instead decreases with the decrease in the magnitude of the
measured voltage quantity. Two different types of dependencies are available:
Multipurpose protection
U=-3U0

I=3Io
MTA line
IEC05000253-2-en.vsdx
Section 6
M13751-326 v4
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