KACO Powador XP500-XP550-HV TL User Manual
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3. REQUIREMENTS FOR MEDIUM-VOLTAGE TRANSFORMERS, THAT ARE CONNECTED
TO 1 CENTRAL INVERTER
The transformer shown in Fig.3 is a double-winding transformer. Its low-voltage side is connected to KACO
central inverter of which rated output voltage is 370V, and its high voltage side is for connection to the
medium-voltage grid in Europe which is 20kV typically. However, other high voltages are also available: 10
kV, 15 kV, 22 kV, 25 kV, 27 kV, 30 kV, 34.5kV or 35 kV etc.
Central Inverter
MV Transformer
Fig. 3 KACO central inverter with Double-winding Transformer
This transformer must comply with the following technical specifications:
1. Equivalent series impedance between low voltage and high voltage winding:
The equivalent series impedance Z(%) of the transformer must be 6 %. Impedance voltage
tolerance limits of 5.4 % ~ 6.6 % must be maintained. This value can be determined when the high-
voltage winding is short-circuited and the voltage on the other low‑voltage winding is increased
until the nominal current flows. (see Fig.4).
Fig.4 Equivalent circuit with short circuited high voltage winding