ABB RET670 - Page 320

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