CHAPTER 6: ACTUAL VALUES
METERING
B30 BUS DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
6-15
6
DELTA-connected instrument transformers
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
* The power system voltages are phase-referenced – for simplicity – to V
AG
and V
AB
, respectively. This, however, is a
relative matter. It is important to remember that the B30 displays are always referenced as specified under
SETTINGS
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
•
ABC phase rotation:
•
ACB phase rotation:
SYSTEM VOLTAGES, sec. V *
VT conn. relay INPUTS, sec. V
SYMM. COMP, sec. V
V
AG
V
BG
V
CG
V
AB
V
BC
V
CA
F5ac
F6ac
F7ac
V
0
V
1
V
2
13.9
∠
0°
76.2
∠
–125°
79.7
∠
–250°
84.9
∠
–313°
138.3
∠
–97°
85.4
∠
–241°
WYE
13.9
∠
0°
76.2
∠
–125°
79.7
∠
–250°
19.5
∠
–192°
56.5
∠
–7°
23.3
∠
–187°
UNKNOWN (only
V
1
and
V
2
can be determined)
84.9
∠
0°
138.3
∠
–144°
85.4
∠
–288°
DELTA
84.9
∠
0°
138.3
∠
–144°
85.4
∠
–288°
N/A
56.5
∠
–54°
23.3
∠
–234°
Summary of Contents for b30
Page 10: ...x B30 BUS DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TABLE OF CONTENTS ...
Page 486: ...5 278 B30 BUS DIFFERENTIAL SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 5 SETTINGS 5 ...
Page 616: ...iv B30 BUS DIFFERENTIAL SYSTEM INSTRUCTION MANUAL ABBREVIATIONS ...
Page 632: ...xvi B30 BUS DIFFERENTIAL SYSTEM INSTRUCTION MANUAL INDEX ...
