[James_H._Harlow]_Electric_Power_Transformer_Engin(BookSee.org)

S1
S2
S3
L1
L2
L3
Series Unit Main Unit
FIGURE 2.3.12 Two-core PST.
FIGURE 2.3.14 Quadrature booster set (300 MVA, 50 Hz, 40012*1.25%/11512*1.45˚ kV).
L
,
,
L
a) b)
S
c)
FIGURE 2.3.15 Winding arrangements.
, L
Y Y
FIGURE 2.3.13 Quadrature booster — simplified connection diagram.
2.3.6 Details of Transformer Design
In general, the design characteristics of PSTs do not differ from ordinary power transformers. In the
symmetrical case, however, the phase-angle difference of the currents flowing through the two parts of
the series winding has to be recognized. The additional magnetic field excited by the self-compensating
components in the series winding influences mechanical forces, additional losses, and the short-circuit
impedance. Figure 2.3.15 shows schematically variations of the physical winding arrangements in PSTs.
In Figure 2.3.15a, a double concentric design of a single-phase PST is shown. This arrangement does
not offer any problems with respect to the phase lag between currents and is a standard winding
arrangement in shell-type transformers. In core types, the arrangement of the connecting leads from the
innermost regulating winding need some attention, but this does not present a real obstacle to the use
© 2004 by CRC Press LLC
© 2004 by CRC Press LLC