49
This setting has the following effects:
The target power factor is attained, on average, in the upper power range.
·
Overcorrection (capacitive, usually disruptive) is avoided in the low load range.
·
An effective combination of parallel shift and limitation is illustrated in
[Figure 49]
.
Figure 49 Control response after setting target cos
φ
= 0.92 ind, limitation = +1.0,
parallel shift = -1.0
This example illustrates:
In the
·
upper power range
, the set cos
φ
is specified as the lower more inductive limit value.
Overcorrection is avoided in the
·
low load range
.
For the sake of completeness, the following
[Figure 50]
shows the characteristics of the control
band when set for a capacitive target cos
φ
. In this case, the control range does not extend late-
rally at the reactive power axis into the regeneration quadrants, but is mirrored from the power
draw side into the regeneration side.
Active power
Reactive power
ind
cap
Regeneration
Switch in
Switch out
One division =
0.65 × smallest cap.
stage
-2
-3
4
3
-1
Active power
Reactive power
ind
cap
Regeneration
Switch in
Switch out
One division =
0.65 × smallest cap.
stage
-3
3
2
-2
Active power
Reactive power
ind
cap
Regeneration
Switch in
Switch out
One division =
0.65 × smallest cap.
stage
-2
-3
4
3
-1
Active power
Reactive power
ind
cap
Regeneration
Switch in
Switch out
One division =
0.65 × smallest cap.
stage
-3
3
2
-2
Figure 50 Control response after setting target cos
φ
= 0.95 cap, limitation = -1.0,
parallel shift = 0
