GE G30 Instruction Manual page 364

SYSTEM SETUP
Table 5-18: Example of delta-wye connected power transformer data
Data
Voltage Phasor Diagram
Phase Shift
Grounding
Rated MVA
Nominal φ-φ Voltage
CT Connection
CT Ratio
Auxiliary Cooling
The abbreviated nomenclature for applicable relay settings is as follows:
Rotation =
SETTINGS  SYSTEM SETUP  POWER SYSTEM  PHASE ROTATION
w =
SETTINGS  SYSTEM SETUP  TRANSFORMER  GENERAL  NUMBER OF WINDINGS
total
Compensation =
SETTINGS  SYSTEM SETUP  TRANSFORMER  GENERAL  PHASE COMPENSATION
Source [w] =
SETTINGS  SYSTEM SETUP  TRANSFORMER  WINDING w  WINDING w SOURCE
P [w] =
SETTINGS  SYSTEM SETUP  TRANSFORMER  WINDING w  WINDING w RATED MVA
rated
5
V [w] =
SETTINGS  SYSTEM SETUP  TRANSFORMER  WINDING w  WINDING w NOM F-F VOLTAGE
nominal
Connection [w] =
SETTINGS  SYSTEM SETUP  TRANSFORMER  WINDING w  WINDING w CONNECTION
Grounding [w] =
SETTINGS  SYSTEM SETUP  TRANSFORMER  WINDING w  WINDING w GROUNDING
Φ[w] =
SETTINGS  SYSTEM SETUP  TRANSFORMER  WINDING w  WINDING w ANGLE WRT WINDING 1
CT primary [w] = the phase CT primary associated with Source [w]
Note that w = winding number, 1 to w
The following transformer setup rules must be observed:
• The angle for the first winding from the transformer setup must be 0°, and the angles for the following windings must
be entered as negative (lagging) with respect to (WRT) the winding 1 angle
• The "Within zone" and "Not within zone" setting values refer to whether the winding is grounded. Select "Within zone"
if a neutral of a wye type winding, or a corner of a delta winding, is grounded within the zone, or whenever a
grounding transformer falls into the zone of protection.
5.5.4.4 Phase relationships of three-phase transformers
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 terminal labels include the characters 1, 2, 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 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 can be a phasor diagram.
In this standard, the arbitrary labeling of the windings is shown as I, II, and III. This standard 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.
5-150
Winding 1
Δ
(delta) connection
0°
In-zone grounding bank
100/133/166 MVA
220 kV
Wye
500/5
Two stages of forced air
total
Winding 2
Y (wye) connection
30° lag (i.e. phases of wye winding lag
corresponding phases of delta winding by 30°)
Ungrounded
100/133/166 MVA
69 kV
Wye
1500/5
Two stages of forced air
G30 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS