NOVAR 2100/2200 Operating Manual
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for usage in power factor control with contactor-type outputs. Such power values are not
displayed, but essential quantity for power factor control – PF control deviation ΔQfh – is evaluated
from them. In the same way, compensation reserves RC and RL are evaluated.
Therefore, the control deviation and the power factor control intentionally do not react on short power
factor deflections that cannot by compensated with contactor-type outputs.
4.7.2 ΣΔQfh – PF Control Deviation
This is crucial quantity for the PF control process. Its value indicates surplus reactive power ( of
fundamental harmonic component ) in the network that must be compensated to reach preset target
power factor. If the value is positive ( inductive character ) the controller connects compensation
capacitors of appropriate power to the network; if negative ( capacitive character ), the controller tries
to add compensation chokes.
Target fundamental harmonic component reactive power of phase L1:
Qfh
T
1
=
Pfh
1
∗
tgφ
T
where :
Pfh1 … phase L1 fundamental harmonic active power
φ
T
… preset target angle between fundamental voltage and current phasors
When target power factor is specified in the
cosφ
format it can be declared :
Target angle (between fundamental U & I phasors) :
φ
T
=
arcsin
(
cosφ
T
)
Then, target fundamental harmonic component reactive power (of phase L1) is :
Qfh
T
1
=
Pfh
1
∗
tg
(
arcsin
(
cosφ
T
))
Finally, the control deviation of phase L1 :
ΔQfh
1
=
Qfh
1
−
Qfh
T
1
where :
Qfh1 … phase L1 fundamental harmonic reactive power
Total three-phase control deviation :
∑
ΔQfh
=
ΔQfh
1
+
ΔQfh
2
+
ΔQfh
3
4.7.3 CHL – Capacitor Harmonic Load Factor
This quantity was designed and implemented in order compensation capacitors protection against
current overload to be possible simply. If appropriate alarm actuation is set the controller disconnects
the sections from a network as soon as the CHL-factor exceeds preset limit value.
Compensation capacitors’ service life depends on not exceeding of operation limits. One of the limits
is capacitors’s maximum current. This may be exceeded with voltage harmonic distortion due to
a capacitor’s inductance being a function of the frequency.
If voltage in not distorted (sinus), the capacitor current is
Ic
=
U
Zc
=
U
1
2
πfC
=
2
πfCU
[ A ]
where :
Ic.... capacitor current
[ A ]
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