ABB RELION 620 Series Technical Manual page 526

Section 4
Protection functions
4.7.3.6
4.7.3.7
520
-R
Relay operation
characteristics
GUID-C7940DC8-04A8-4FED-B089-DAA9B21D50DB V2 EN
Figure 248: Typical impedance locus in underexcitation: a) heavy load b) light load c)
fault in the network
Base values
In this function block, some of the settings are set in per unit (pu). These pu values are
relational to certain base values, for example the values given in A, kV and kVA. The
protection relay supports alternative base value groups for the phase current or voltage-
related settings, for example "Phase Grp 1", "Phase Grp 2" and "Phase Grp 3". Similarly,
"Residual Grp 1", "Residual Grp 2" and "Residual Grp 3" are supported for the residual
current or voltage-related settings. One of the groups must be selected to be used with the
Base value Sel phase or Base value Sel Res settings.
Signals
Table 378: 40 Input signals
Name Type
I3P GROUP
SIGNAL
U3P GROUP
SIGNAL
EXT_LOS_DET BOOLEAN
Table continues on next page
X (Reactance)
c
a
a) Z locus in under excitation for heavily loaded machine
b) Z locus in under excitation for lightly loaded machine
-X
c) Z locus for a fault in the network
Default Description
0.0 Group signal for current inputs
0.0 Group signal for voltage inputs
0=False External signal for excitation loss detection
1MAC504801-IB E
R (Resistance)
b
620 series ANSI
Technical Manual