GE N60 Instruction Manual page 379

CHAPTER 6: ACTUAL VALUES
For display and oscillography purposes, all phasor angles in a given relay are referred to an AC input channel pre-selected
by the
SETTINGS  SYSTEM SETUP  POWER SYSTEM  FREQUENCY AND PHASE REFERENCE
particular AC signal source to be used as the reference.
If the AC signal pre-selected by the relay upon configuration is not measurable, the phase angles are not referenced. The
phase angles are assigned as positive in the leading direction, and are presented as negative in the lagging direction, to
more closely align with power system metering conventions. The figure illustrates this.
-180
6.3.1.3 UR convention for measuring symmetrical components
The URs calculate voltage symmetrical components for the power system phase A line-to-neutral voltage, and
symmetrical components of the currents for the power system phase A current. Owing to the above definition, phase
angle relations between the symmetrical currents and voltages stay the same irrespective of the connection of instrument
transformers. This is important for setting directional protection elements that use symmetrical voltages.
For display and oscillography purposes the phase angles of symmetrical components are referenced to a common
reference as described in the previous sub-section.
WYE-connected instrument transformers
• ABC phase rotation:
1

V_0 = -- V + V
AG
3
1

V_1 = -- V + aV
AG
3
1

V_2 = -- V + a
AG
3
The above equations apply to currents as well.
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
Figure 6-2: UR phase angle measurement convention
o
-270
o
-225
o
o
-135
o
-90

+ V
BG CG
2

+ a V
BG CG
2

V + aV
BG CG
o
-315
positive
angle
direction
o
0
UR phase angle
reference
o
-45
827845A1.CDR
• ACB phase rotation:
1

V_0 = -- V + V
AG
3
1

V_1 = -- V + a
AG
3
1

V_2 = -- V + aV
AG
3
METERING
setting. This setting defines a

+ V
BG CG
2

V + aV
BG CG
2

+ a V
BG CG
6-13
6