ABB REL650 Applications Manual page 167

1MRK 506 334-UUS A
Application manual
2
V 380
min
= =
Z
L min
S 1000
max
EQUATION1736-ANSI V1 EN
The minimum load resistance R
equal to equation 76.
(
j
= ×
R Z cos
L min L min
EQUATION1338 V1 EN
The system impedance Z
machine system, see figure 76. Its value is calculated according to equation 77.
= + +
Z Z Z Z
S SA 1 L 1 SB 1
EQUATION1339 V1 EN
The calculated value of the system impedance is of informative nature and helps
determining the position of oscillation center, see figure 77, which is for general case
calculated according to equation 78.
Z
= -
Z S Z
CO SA 1
E
B
+
1
E
A
EQUATION1340 V1 EN
In particular cases, when
=
E E
A B
EQUATION1342 V1 EN
resides the center of oscillation on impedance point, see equation 80.
Z
(
= - =
Z S Z 7.43
CO SA 1
2
EQUATION1341 V1 EN
2
= W
144.4
at maximum load and minimum system voltage is
Lmin
)
= × =
144.4 0.95 137.2
max
is determined as a sum of all impedance in an equivalent two-
S
( )
= + W
17.16 j 154.8
)
+ W
j 33.9
Section 6
Impedance protection
W
(Equation 75)
(Equation 76)
(Equation 77)
(Equation 78)
(Equation 79)
(Equation 80)
161