ABB RET670 Applications Manual page 320

Section 3
IED application
314
LdAngle
LdAngle
RLdRv
ANSI10000192 V1 EN
Figure 138: Load encroachment characteristic
The calculation of the apparent load impedance Z
Z can be done according to equations:
loadmin
V
Zload = min
×
3 I
max
EQUATION1754-ANSI V1 EN
2
V
=
Zload min
S
EQUATION1753-ANSI V1 EN
Where:
V is the minimum phase-to-phase voltage in kV
S is the maximum apparent power in MVA.
The load angle LdAngle can be derived according to equation 240:
X
RLdFw
LdAngle
LdAngle
ANSI10000192_1_en.vsd
and minimum load impedance
load
1MRK504116-UUS C
R
(Equation 238)
(Equation 239)
Application manual