GE L60 Instruction Manual page 446

Line phase comparison system, ur series
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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 L60 displays are always referenced as specified under

SYSTEM SETUP
The example above is illustrated in the following figure.
6
Figure 6–3: 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
L60 Line Phase Comparison 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

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