GE B30 Instruction Manual page 501

CHAPTER 6: ACTUAL VALUES
DELTA-connected instrument transformers
• ABC phase rotation:
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 V
UNKNOWN (only and
1 2
can be determined)
* The power system voltages are phase-referenced – for simplicity – to V
relative matter. It is important to remember that the B30 displays are always referenced as specified under
SYSTEM SETUP  POWER SYSTEM  FREQUENCY AND PHASE REFERENCE
The example above is illustrated in the following figure.
Figure 6-5: Measurement convention for symmetrical components
B30 BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
VT conn. relay INPUTS, sec. V
V V V
AB BC CA
84.9 138.3 85.4 WYE
∠–313° ∠–97° ∠–241°
84.9 138.3 85.4 DELTA
∠0° ∠–144° ∠–288°
• ACB phase rotation:
F5ac F6ac F7ac
13.9 76.2 79.7
∠0° ∠–125° ∠–250°
84.9 138.3 85.4
∠0° ∠–144° ∠–288°
and V , respectively. This, however, is a
AG AB
.
METERING
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 
6-15
6