GE B30 UR Series Instruction Manual page 352

6.3 METERING
b) UR CONVENTION FOR MEASURING SYMMETRICAL COMPONENTS
The UR-series of relays 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 refer-
ence as described in the previous sub-section.
WYE-CONNECTED INSTRUMENT TRANSFORMERS:
• ABC phase rotation:
6
1
-- - V
V_0 (
=
3
1
V_1 -- - V (
=
3
1
V_2 -- - V (
=
3
The above equations apply to currents as well.
6-12
o
-225
o
-180
o
-135
Figure 6–1: UR PHASE ANGLE MEASUREMENT CONVENTION
V V )
+ +
AG BG CG
2
aV a V )
+ +
AG BG CG
2
a V aV )
+ +
AG BG CG
B30 Bus Differential System
o
-270
o
-315
positive
angle
direction
o
0
UR phase angle
reference
o
-45
o
-90
• ACB phase rotation:
1
-- - V
V_0
=
3
1
-- - V
V_1
=
3
1
-- - V
V_2
=
3
6 ACTUAL VALUES
827845A1.CDR
( )
V V
+ +
AG BG CG
2
( a V aV )
+ +
AG BG CG
2
( aV a V )
+ +
AG BG CG
GE Multilin