Hitachi Relion 670 Series Applications Manual page 70

Section 4
Analog inputs
V
=
Ph Ph
3 Vo
EQUATION1927-ANSI V1 EN-US
The primary rated voltage of such VT is always equal to VPh-Gnd. Therefore, three series connected VT
secondary windings will give the secondary voltage equal only to one individual VT secondary winding
rating. Thus the secondary windings of such open delta VTs quite often has a secondary rated voltage
close to rated phase-to-phase VT secondary voltage, that is, 115V or 115/√3V as in this particular
example. Figure
available to the built-in protection and control functions within the IED.
138
138 kV
3
115 V
3
138 kV
3
115 V
3
ANSI06000602 V2 EN-US
Figure 23: Open delta connected VT in low impedance or solidly grounded power system
64
- =
V
-
Ph Gnd
3
23 gives an overview of the actions which are needed to make this measurement
A
B
C
kV
3
115 V
3
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IED
2
13
AI07 (I)
14
15
AI08 (V)
16
17
AI09 (V)
18
1
3
19
AI10 (V)
20
21
+3Vo
AI11 (V)
22
23
AI12 (V)
24
1MRK511407-UUS Rev. N
SMAI2
BLOCK
^GRP2_A
# Not Used
# Not Used
^GRP2_B
# Not Used
^GRP2_C
^GRP2N
TYPE
4
ANSI06000602-2-en.vsd
Phasor measurement unit RES670
Application manual
(Equation 7)
5
AI3P
AI1
AI2
AI3
AI4
AIN