ABB REC670 Applications Manual page 454

Section 14
Control
448
Assume that we want to achieve that j
D = ´
V Z I
ß
0
j j
-
j 90 j j j (
D = ´ =
Ve Ze Ie ZIe
1
ß
0
- = j + j
90
1
ß
0
j = - - j
90
1
EQUATION1983-ANSI V1 EN-US
If for example cosj = 0.8 then j = arcos 0.8 = 37°. With the references in figure 181, j
will be negative (inductive load) and we get:
j = - -
- = -
0 0
( 37 ) 90
1
EQUATION1939 V1 EN-US
To achieve a more correct regulation, an adjustment to a value of j2 slightly less than
-90° (2 – 4° less) can be made.
The effect of changing power factor of the load will be that j2 will no longer be close
to -90° resulting in V being smaller or greater than V
L
adjusted.
shows an example of this where the settings of Rline and Xline for j = 11°
Figure 182
has been applied with a different value of j (j = 30°).
from figure 181
= -90°, then:
2
j j
+
)
1
0
53
1MRK 511 401-UUS A
(Equation 124)
(Equation 125)
if the ratio Rline/Xline is not
B
Bay control REC670 2.2 ANSI
Application manual