[James_H._Harlow]_Electric_Power_Transformer_Engin(BookSee.org)

FIGURE 2.7.18 One movable contact on stationary contact (asymmetrical position).
FIGURE 2.7.16 Single-phase step-voltage regulator tap changer.
FIGURE 2.7.19 Two movable contacts on adjacent stationary contacts (bridging position).
FIGURE 2.7.17 Two movable contacts on the same stationary contact (symmetrical position).
SL–TAP 2: both contacts are closed on TAP 2; symmetrical position as shown in Figure 2.7.17.
SL–a: one contact is closed on TAP 2; asymmetrical position as shown in Figure 2.7.18. TAP 2–a is
the voltage drop across the reactor half.
SL–b: movable contacts are located on adjacent stationary contacts TAP 1 and TAP 2; bridging position
as shown in Figure 2.7.19.
SL–c: one contact is closed on TAP 1, asymmetrical position. TAP 1–c is the voltage drop across the
reactor half.
SL–TAP 1: both contacts are closed on TAP 1, symmetrical position.
TAP 1–c and TAP 2–a are reactance voltages introduced into the circuit by the reactor in the asymmetrical
positions. TAP 1–e and TAP 2–d represent the total reactor voltage. TAP 2–e represents the
voltage ruptured when bridging position is opened at TAP 2, while TAP 1–d represents the voltage
ruptured if bridging position is opened at TAP 1.
FIGURE 2.7.20 Voltage phasor diagrams involved in a tap change.
© 2004 by CRC Press LLC
© 2004 by CRC Press LLC