ABB Relion 670 Series RES670, Technical Manual

Page: 344 / 888

V=-3V0
Operate region
RCADir
ROADir
Ipickup
I=3Io
mta line
F
en05000253_ansi.vsd
ANSI05000253 V1 EN
Figure 112: CVGAPC, IcosPhi&V 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
192 ). 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:
• Voltage restraint overcurrent (when setting parameter VDepMode_OC1 = Slope )
Section 11
1MRK 511 365-UUS A
Multipurpose protection
338 Phasor measurement unit RES670 2.1 ANSI
Technical manual