KMB NOVAR-1 Series, Руководство по эксплуатации

Страница: 45 / 77

Novar 1xxx KMB systems
45
Example :
A compensation capacitor with a nominal value of 5 kvars is permanently connected to a power
transformer, which is before the controller CT. It is required to control the target power factor of 1.00,
which is to be registered by an electricity meter, measuring whole transformer load. The controller can
then be set as follows:
•
set target power factor in parameter 01 to 1.00
•
Turn the offset control on, i.e. set the parameter 63 to 1
•
Set the offset power, i.e. parameter 05 to 5 (kvars)
When, for example, an active load of 15 kW occurs, then balanced state will be reached at power
factor of approximately 0.95 (measured by the controller). This value corresponds to the ratio of 5kvar
/ 15 kW. In other words, the controller will intentionally undercompensate by 5 kvar at the connected
network point in order the target power factor of 1.00 to be reached in the electricity meter connection
point, where the permanent capacitor comes to the effect.
When the offset control is activated, the limit power factor for compensation by choke parameter value
gets irrelevant - see the parameter 27 description.
4.2 Section Value Accurization
If the controller is set up to automatic section power recognition process, that means parameter 20 is
set to
AC=A
AC=A AC=A
AC=A
, or
AC=1
AC=1 AC=1
AC=1
, it carries out the automatic section power recognition process on the first
initialization or reinitialization or on resuming power after a power failure.
After successful completion of the automatic section power recognition process, it records all the
power values measured and starts the control process. All power values measured are tagged as “not
yet precise”. A sections, the value of which is not yet precise, can be identified by
slowly flashing
decimal point (as opposed to fast flashing decimal point to identify a disabled section – see description
further below).
The controller measures the sections continually within the control process as they are connected and
disconnected. It evaluates the average value measured for each not-yet-precise section and, when
having received about 100 values, it rewrites the original section value, which was obtained in the
automatic section power recognition process, with it. At the same time it tags the section as “precise”
and stops further accurization of such a section.
This way, possible inaccuracies in the automatic section power recognition process are removed.
If the sections’ values are specified manually (using the switching program and smallest capacitor
power or by editing section value in parameter 25), no subsequent accurization takes place. Neither is
accurization of choke sections, if present, carried out.
If the automatic section power recognition process is enabled, the accurization process can be
automatically started anytime during the control process as well. If the controller detects that
a compensation capacitor has repeatedly been showing a value different from that measured in the
automatic section power recognition process and the difference is not in order of magnitude (that is in
the interval from a half to double value) from the value recorded in the controller, the accurization
process for such a section will start. Thus effects of changes in compensation capacitor values, for
example as a consequence of the forming process after installation or due to aging etc., can be
eliminated.