GE T60 Instruction Manual page 256

5.4 SYSTEM SETUP
c) WINDINGS 1 TO 6
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PATH: SETTINGS SYSTEM SETUP
 WINDING 1

The settings specific to each winding are shown above.
Transformer differential protection uses the following calculated quantities (per phase): fundamental, second harmonic, and
fifth harmonic differential current phasors, and restraint current phasors. This information is extracted from the current
5 transformers (CTs) connected to the relay by correcting the magnitude and phase relationships of the currents for each
winding, so as to obtain zero (or near zero) differential currents under normal operating conditions. Traditionally, these cor-
rections were accomplished by interposing CTs and tapped relay windings with some combination of CT connections.
The T60 simplifies these configuration issues. All CTs at the transformer are connected wye (polarity markings pointing
away from the transformer). User-entered settings in the relay characterizing the transformer being protected and allow the
relay to automatically perform all necessary magnitude, phase angle, and zero-sequence compensation.
This section describes the algorithms in the relay that perform this compensation and produce the required calculated
quantities for transformer differential protection, by means of the following example of a delta-wye (Δ-Y) connected power
transformer with the following data:
Table 5–13: EXAMPLE 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
w =
SETTINGS
total
Compensation =
SETTINGS
Source [w] =
SETTINGS
5-110
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TRANSFORMER
WINDING 1 SOURCE:
SRC 1
WINDING 1 RATED MVA:
MESSAGE
100.000 MVA
WINDING 1 NOM φ-φ
MESSAGE
VOLTAGE:
WINDING 1
MESSAGE
CONNECTION: Wye
WINDING 1 GROUNDING:
MESSAGE
Not within zone
WINDING ~ ANGLE WRT
MESSAGE
WINDING 1:
WINDING 1 RESISTANCE
MESSAGE
3φ: 10.0000 ohms
WINDING 1
Δ
(DELTA) CONNECTION
0°
In-zone grounding bank
100/133/166 MVA
220 kV
Wye
500/5
Two stages of forced air
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SYSTEM SETUP
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SYSTEM SETUP
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SYSTEM SETUP
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SYSTEM SETUP
T60 Transformer Protection System
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WINDING 1(6)
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
(or the user-defined name)
Range: 0.001 to 2000.000 MVA in steps of 0.001
Range: 0.001 to 2000.000 kV in steps of 0.001
220.000 kV
Range: Wye, Delta, Zig-zag
Range: Not within zone, Within zone
Range: –359.9 to 0.0° in steps of 0.1, ('~' > 1)
(shown when viewed Winding is not Winding 1)
0.0°
Range: 0.0001 to 100.0000 ohms in steps of 0.0001
30° lag (i.e. phases of wye winding lag
corresponding phases of delta winding by 30°)
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POWER SYSTEM PHASE ROTATION
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TRANSFORMER GENERAL
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TRANSFORMER GENERAL
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TRANSFORMER WINDING w
5 SETTINGS
WINDING 2
Y (WYE) CONNECTION
Ungrounded
100/133/166 MVA
69 kV
Wye
1500/5
Two stages of forced air
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NUMBER OF WINDINGS
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PHASE COMPENSATION

WINDING w SOURCE
GE Multilin