Assume that we want to achieve that
j
2
= -90°, then:
0
1
1
(
)
90
0
1
0
1
90
90
j
j j
j
j j
j
j
+
-
D = ´
ß
D
=
´
=
ß
-
=
+
ß
= - -
j
j
j
j
V
Z I
Ve
Ze
Ie
ZIe
EQUATION1983-ANSI V1 EN-US
(Equation 513)
If for example cos
j
= 0.8 then
j
= arcos 0.8 = 37°. With the references in figure
,
j
will be negative (inductive load) and we get:
0
0
0
1
( 37 ) 90
53
j
= - -
-
= -
EQUATION1939 V1 EN-US
(Equation 514)
To achieve a more correct regulation, an adjustment to a value of
j
2 slightly less than
-90° (2 – 4° less) can be made.
The effect of changing power factor of the load will be that
j
2 will no longer be close
to -90° resulting in V
L
being smaller or greater than V
B
if the ratio Rline/Xline is not
adjusted.
Figure
shows an example of this where the settings of
Rline
and
Xline
for
j
= 11°
has been applied with a different value of
j
(
j
= 30°).
1MRK 504 163-UUS A
Section 15
Control
Transformer protection RET670 2.2 ANSI
795
Application manual
Summary of Contents for RELION RET670
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