ABB Relion 670 Series Technical Reference Manual page 280

Section 9
Multipurpose protection
274
• the magnitude of the measured current is bigger than the set pick-up level
• the phasor of the measured current is within the operating region (defined by
the relay operate angle, ROADir parameter setting; see figure 137).
RCADir
Ipickup
ROADir
Operate region
IEC05000252 V1 EN
Figure 137: I & U directional operating principle for CVGAPC function
where:
RCADir is -75°
ROADir is 50°
The second principle, referred to as "IcosPhi&U" in the parameter setting tool,
checks that:
• 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 137).
U=-3U0
I=3Io
mta line
en05000252.vsd
1MRK 505 208-UEN B
Technical reference manual