KACO Powador XP500-XP550-HV TL - Manual (Page 6)

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2. Equivalent series impedance Z(%) of the double-winding transformer:
To summarize of the contents in Article 2, the equivalent series impedance Z(%) of the double-
winding transformer can be shown as followed.
Z
L
is the equivalent series impedance of low voltage winding, and Z
H
is the equivalent series
impedance of high voltage winding.
Z
H
(1%) Z
La
(5%)
Fig. 5 Equivalent series impedance Z(%) of double-winding transformer
3. No neutral point is required on the low voltage side. Nevertheless, if a neutral point shows up on
the low‑voltage side, this neutral point must not be either connected or grounded.
4. Double-winding transformers with varying windings each on the high‑voltage side and the
low‑voltage side can be used. For example YNd11, YNd5, YNd1 or Dy11, Dy5, Dy1 with an
ungrounded neutral point on the low‑voltage side (see Fig.6)
Fig. 6 Diagram of double-winding transformer