GE 745 Instruction Manual page 104

AUTO-CONFIGURATION
5.2.3 Phase Shifts on Three-phase Transformers
5–8
R
ZERO POSITION
TERMINAL
(to TAP POSITION -)
The "zero position" terminal and the "wiper" terminal of the tap position circuit are
connected to the positive and negative 745 tap position terminals. Polarity is not
consequential. The following setpoints configure the 745 to determine tap position. In the
S2 SYSTEM SETUP ONLOAD TAP CHANGER

WINIDNG WITH TAP CHANGER: "Winding 2"
NUMBER OF TAP POSITIONS: "33"
MINIMUM TAP POSITION
VOLTAGE INCREMENT PER
RESISTANCE INCREMENT PER
The maximum value resistance on the top tap is 5 kΩ.
Power transformers that are built in accordance with ANSI and IEC standards are required
to identify winding terminals and phase relationships among the windings of the
transformer.
ANSI standard C.37.12.70 requires that the labels of the terminals include the characters 1,
2, and 3 to represent the names of the individual phases. The phase relationship among
the windings must be shown as a phasor diagram on the nameplate, with the winding
terminals clearly labeled. This standard specifically states that the phase relationships are
established for a condition where the source phase sequence of 1-2-3 is connected to
transformer windings labeled 1, 2 and 3 respectively.
IEC standard 60076-1 (1993) states that the terminal markings of the three phases follow
national practice. The phase relationship among the windings is shown as a specified
notation on the nameplate, and there may be a phasor diagram. In this standard the
arbitrary labeling of the windings is shown as I, II, and III. This standard specifically states
that the phase relationships are established for a condition where a source phase
sequence of I - II - III is connected to transformer windings labeled I, II and III respectively.
R R
R
TAP 4
TAP 3
R
TAP 2
WIPER
AT TAP 5
TAP 1
ZERO
POSITION
WIPER
TERMINAL
(to TAP POSITION +)
FIGURE 5–1: Tap position input
setpoint menu, make the following settings:
VOLTAGE: "61.0 kV"
TAP: "0.50 kV"
TAP: "33 Ω"
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETPOINTS
R
TAP 6
R
TAP 7
R
TAP 8
R
TAP 9
etc.