Page 55 - ELECTRONICON_Katalog_PFC-60Hz

DEFINITIONS AND SELECTION CRITERIA

II. Adapted Rating:
The adapted reactor is designed to create – in combination with a specially sized capacitor - exactly the desired output of
reactive power, allowing for the internal voltage rise inside the resonating circuit.
Advantage: The exact power is installed as required by the customer, and switching devices are stressed less.

25kvar 480V 60Hz to be detuned to 227Hz (p = 7%)
Example

Step 1: Calculation of the capacitor Calculation

Current for the power factor
Voltage at capacitor terminations Adjustment of necessary capacitance
I
correction of 25 kvar 400 V 50 Hz C = = 52.1 A
C
25000 var U = U mains 480 V = 516.1 V 2 πf · U 516.1 V · 2 π · 60 Hz
=
Q c
I = = = 52.1 A C 1-p 1-0.07 C
C
U mains 480 V = 268 μF
268μF = 3× 89μF 265.286-708900 “27.7 kvar 525V 60Hz” (page 29)
Step 2: Calculation of the reactor
DEFINITIONS AND SELECTION CRITE-
Capacitor Reactance Required reactance of the reactor Required inductance
X
1
1
X = = = 9.9 Ω X = X ⋅ p = 9.9 Ω ⋅ 0.07 = 0.693 Ω L = = 0.693 Ω = 1.838 mH
L
C

2 πf · C 2 π · 60 Hz · 268 μF L C 2 πf 2 π · 60 Hz
> 444.125-4837A0 “Fk-Dr 25/480/60/7/Dla“ (page 64)
RIA
Step 1: Determination of the reactor Selection
Alternatively, reactors matching the most common capacitor ratings can be selected directly from our data charts of reactors from catalogue
with “adapted rating” (page 64):

Look up the mains voltage 480 V Select the required output power Find 444.125-4837A0
of the capacitor branch under
in combination with 7 %
“Power Output Q (U )”: 25 kvar “FK-Dr 25/480/60/7/Dla“
N
LC
Step 2: Determination of the matching capacitor

Look up the corresponding capacitance Select a proper capacitor with the capacitance found under 1.) from the data
value in column “Capacitor C”: 3 × 89 μF charts for capacitors on pages 26 to 33. Make sure to obey the minimum
voltage rating U for the capacitor as stated in the chart (here: ≤ 525 V).
C

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