Functioning and operation
33
5 Functioning and operation
The control relay runs completely automatically
after it has been connected and started. The
current power factor appears in the digital
display (c). The ind and cap LEDs (b) show
whether the network is loaded with capacitive
or inductive reactive power.
At the same time, the stage indicator (a)
shows the switched capacitor stages.
5.1 Automatic control mode
In automatic control mode the control relay
constantly measures the current power factor in
the network and compares this with the target
power factor. If deviations are identied that are
in excess of the tolerance range (control band),
the required target power factor is restored by
activating or deactivating specic capacitor
stages within the control relay delay time and in
accordance with the capacitor discharge time.
The control relay delay time is adapted to the
size of the deviation. The greater the deviation,
the shorter the reaction time. In contrast, the
capacitor discharge time is xed at one minute.
In addition, the control relay monitors the
overcurrent in the capacitors and checks whether
the connected capacitor power is sufcient for
compensation. If automatic response current
identication is activated, the control relay also
checks the power of the capacitors connected.
The control relay issues an alarm in the event
of an error. (see section 6)
5.2 Displaying the total harmonic
distortion factor
If the control relay is in automatic control relay
mode and if no historical or current alarm is
pending, then pressing the ”Voltage THD”
key (h) will display the current total harmonic
distortion factor (thd) of the voltage in %.
5.3 Check System
Simultaneously pressing ”Voltage THD”
(h) and ”Select” (i) displays the current
relative value of stage 1. The value displayed
alternately with ”A1” in the display (see section
6.2.2). It is acknowledged automatically for
each stage after about 15 seconds or can be
acknowledged earlier by pressing any key.
Simultaneously pressing ”Voltage THD” (h)
and ”Select” (i) for about 3 seconds brings
the control relay into check system mode.
If automatic response current identication
(setup code -4-) is activated, then the control
relay behaves as described in section 3.1
„Initial start-up“.
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