NOVAR 2100/2200 Operating Manual
On low loads (zone A) and on medium loads (zone B), the control bandwidth is constant and
corresponds to the
O
MIN
value ( reactive power of the minimum output ) – the band follows the power
factor slope specified at width ±(
O
MIN
)/2. On high loads (zone C) the bandwidth increases so its limits
correspond to adjustable deviation from the target power factor. For the cosinus target power factor
format , the standard bandwidth value in this zone is 0.010 or ± 0.005 – this condition is shown in the
figure. If thus, for example, the target power factor is specified as 0.98, reactive power corresponding
to power factor from 0.975 to 0.985 will be considered compensated condition in zone C.
The control bandwidth format is the same as the target power factor. It can be set in range
0.000÷0.040 if the target power factor format is
cosinus
; if the format is
tangens
or
angle
, the control
bandwidth range is 0.000÷0.030 or 0÷15°, respectively.
Control bandwidth increase may especially be useful in systems with large control range – avoiding
uselessly precise control on high loads reduces the number of control interventions which results in
longer contactor service life. If the parameter values is decreased to 0, the control bandwidth
corresponds to value
O
MIN
(constant, not widening).
Note: On low loads, the control bandwidth is “bent” (zone A) to prevent undesired overcompensation
(the illustration is a simplification).
4.3.3.3 Control Time for Tariff 1/2, No. 02/07
Power factor control passes discontinuously as a sequence of
control interventions
. The period
between two consecutive control interventions is called
control time
.
The values for tariff 1 and tariff 2 can be specified in the range from 5 seconds to 20 minutes. It can be
set different for undercompensation (marked as
UC
, in line 2) and overcompensation (
OC
, line 3)
cases.
The value specified determines the frequency of control interventions under the following conditions:
•
instantaneous power factor is either more inductive than the value required –
undercompensated – or more capacitive – overcompensated
•
the difference between reactive power instantaneous value in the power system and optimum
value, which corresponds to the target power factor setting (= control deviation,
ΔQfh
), is just
equal to the smallest output reactive power (
O
MIN
)
If the parameter value is set to say 3 minutes and the above mentioned conditions are met in the
power system, the controller calculates optimum compensation and carries out control intervention
every 3 minutes.
The time mentioned gets shorter in proportion to the instantaneous control deviation. If control time
without additional character “L” is set, it gets shorter as square of control deviation over the smallest
output reactive power (
O
MIN
). If the control time with additional character “L” is specified, it gets shorter
in proportion to this ratio (“
L
” = Linear, causes slower response to large deviations). Rising control
deviation can decrease this value to the minimum control time of 5 seconds.
On the contrary, if the
ΔQfh
control deviation is smaller than the smallest output reactive power (
O
MIN
),
control time gets twice as long. If the control deviation falls further under half of the smallest capacitive
section current value (
O
MIN
), no control interventions take place.
The control time countdown can be checked in the 3
rd
line of the three-phase control deviation
ΣΔQfh
window.
4.3.3.4 Offset Power for Tariff 1/2, No. 03/08
These parameters are meaningful when
offset control
(parameter 13, see below) is activated only.
Unless this control mode is active, they do not appear.
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