NOVAR 2100/2200 Operating Manual
After the step is switched off, its type and size is displayed : in the example above, (nominal) reactive
power of 7.38 kvar, capacitive.
The three bars in the second line (behind the output number) mean that three-phase type (C123)
capacitor is supposed.
Note : The recognized output powers are not displayed as actual power values but
the
nominal power
values, that is the values that correspond to the preset nominal voltage
U
NOM
of the network.. It is supposed that the metering current transformer ratio and the metering
voltage transformer ratio, if any, are set correctly.
If a step power was detected as zero, either the output is not used (nothing connected to it) or the step
power is too small to be recognized automatically.
If the controller does not succeed in determining a output’s value, it does not show it – dashes
-
-
-
are displayed instead. This condition occurs if reactive power value in the power system fluctuates
considerably due to changes in load.
The process has 3 or 6 rounds – round number is displayed momentarily at the beginning of the round
in the first line.
After carrying out three rounds, partial evaluation is carried out. If measurements in the rounds carried
out provides sufficiently stable results, the AOR process is completed. Otherwise the controller carries
out up to three more rounds.
A requirement for successful AOR process is sufficiently stable condition of the power system – while
connecting or disconnecting a section, the reactive load power must not change by a value which is
comparable with, or even greater than, the reactive power value of the section under test. Otherwise
the measurement result is unsuccessful. As a rule of thumb, the section values are recognized the
more precisely, the lower the load is in the power system.
Ongoing AOR process can be cancelled at any point either manually by switching display into
parameters with the
key or by any of alarm actuations. In such case, the recognized data are
neglected and output setting is not updated.
On completion of the total process, the controller saves recognized output types and sizes into its
memory. Then , if at least one section with non-zero total reactive power has been detected, the
controller starts power factor control.
Otherwise, if the previous AOR process unsuccessful (no valid outputs found or cancelled
prematurely), the process is automatically relaunched each approximately 15 minutes again in the
control mode.
It is strongly recommended to check recognized section values in parameter 25 after the
AOR process has passed. If any doubt about the recognized values you can start the AOR
process again or, if necessary, to edit the section values manually. It is often necessary at
the lowest power sections especially when the AOR process run while high load at the
network – such sections can be recognized as zero outputs and needs to be set manually.
Sometimes it is necessary to start the AOR process at disconnected load (or at zero load )–
for example ,when testing a compensation switchboard before its expedition to a customer. If
the default controller undercurrent (
I<
) alarm ( No. 04, parameter 43) actuation is set the
controller gets into the standby state in such case and the AOR process cannot be started.
Therefore, it is necessary to switch this alarm actuation temporarily off ( and to return it back
after the AOR-process passes).
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