GE B30 Instruction Manual page 336

6.3 METERING
DELTA-CONNECTED INSTRUMENT TRANSFORMERS:
• ABC phase rotation:
V_0 N/A
=

1
–
-------------------- V
V_1
=
3 3

1 30
---------------- - V
V_2
=
3 3
The zero-sequence voltage is not measurable under the Delta connection of instrument transformers and is defaulted to
zero. The table below shows an example of symmetrical components calculations for the ABC phase rotation.
Table 6–1: SYMMETRICAL COMPONENTS CALCULATION EXAMPLE
SYSTEM VOLTAGES, SEC. V *
V V V
AG BG CG
13.9 76.2 79.7
0° –125° –250°
V
UNKNOWN (only 1 and
can be determined)
* The power system voltages are phase-referenced – for simplicity – to VAG and VAB, respectively. This, however, is a
relative matter. It is important to remember that the B30 displays are always referenced as specified under

SYSTEM SETUP
The example above is illustrated in the following figure.
6
Figure 6–2: MEASUREMENT CONVENTION FOR SYMMETRICAL COMPONENTS
6-12

30
2
 
aV a V
+ +
AB BC CA
2
 
a V aV
+ +
AB BC CA
V V V
AB BC CA
84.9 138.3 85.4
–313° –97° –241°
V 84.9 138.3 85.4
2
0° –144° –288°
 
POWER SYSTEM FREQUENCY AND PHASE REFERENCE
SYSTEM VOLTAGES
A
C
A
C
B30 Bus Differential System
• ACB phase rotation:
V_0 N/A
=

1 30

---------------- - V
V_1
=
3 3
 
1 30
–
-------------------- V
V_2
=
3 3
VT RELAY INPUTS, SEC. V
CONN.
F5AC F6AC F7AC
WYE 13.9 76.2 79.7
0° –125° –250°
DELTA 84.9 138.3 85.4
0° –144° –288°
.
SYMMETRICAL
COMPONENTS
WYE VTs
B
2
DELTA VTs
B
2
6 ACTUAL VALUES
2

a V aV
+ +
AB BC CA
2
 
aV a V
+ +
AB BC CA
SYMM. COMP, SEC. V
V V V
0 1 2
19.5 56.5 23.3
–192° –7° –187°
N/A 56.5 23.3
–54° –234°
SETTINGS
1
0
1
827844A1.CDR
GE Multilin