GE T35 Instruction Manual page 210

5.4 SYSTEM SETUP
Table 5–6: EXAMPLE DELTA-WYE CONNECTED POWER TRANSFORMER DATA
DATA
Voltage Phasor Diagram
Phase Shift
Grounding
Rated MVA
Nominal - Voltage
CT Connection
CT Ratio
Auxiliary Cooling
The abbreviated nomenclature for applicable relay settings is as follows:
Rotation =
SETTINGS
w =
SETTINGS
total
Compensation =
SETTINGS
Source [w] =
SETTINGS
P [w] =
SETTINGS
rated
V [w] =
SETTINGS
nominal
Connection [w] =
SETTINGS
5
Grounding [w] =
SETTINGS
[w]
=
SETTINGS
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:
1. 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.
2. 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.
d) 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 indi-
vidual 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 condi-
tion 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 rela-
tionship 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 rela-
tionships 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.
The reason the source phase sequence must be stated when describing the winding phase relationships is that these rela-
tionships change when the phase sequence changes. The example shown below shows why this happens, using a trans-
former described in IEC nomenclature as a type "Yd1" or in GE Multilin nomenclature as a "Y/d30."
5-76
WINDING 1

(DELTA) CONNECTION
0°
In-zone grounding bank
100/133/166 MVA
220 kV
Wye
500/5
Two stages of forced air
 
SYSTEM SETUP POWER SYSTEM
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
 
SYSTEM SETUP TRANSFORMER
total
T35 Transformer Protection System
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

PHASE ROTATION
 
GENERAL NUMBER OF WINDINGS
 
GENERAL PHASE COMPENSATION
 
WINDING w WINDING w SOURCE
 
WINDING w WINDING w RATED MVA
 
WINDING w NOM  VOLTAGE
WINDING w
 
WINDING w WINDING w CONNECTION
 
WINDING w WINDING w GROUNDING
 
WINDING w WINDING w ANGLE WRT WINDING 1
5 SETTINGS
GE Multilin