ABB Relion REC670 Applications Manual page 79

1MRK 511 358-UEN A
U
=
3 Uo
EQUATION1926 V1 EN-US
The primary rated voltage of such VT is always equal to UPh-E 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
are needed to make this measurement 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
IEC06000602 V4 EN-US
Figure 23: Open delta connected VT in low impedance or solidly earthed power system
Application manual
- =
Ph Ph
U
-
Ph E
3
L1
L2
L3
kV
3
115 V
3
23
IED
2
3
1
+3Uo
gives an overview of the actions which
SMAI2
BLOCK
REVROT
# Not Used
^GRP2L1
# Not Used
^GRP2L2
^GRP2L3
# Not Used
^GRP2N
4
IEC06000602-4-en.vsdx
Section 4
Analog inputs
(Equation 7)
5
AI3P
AI1
AI2
AI3
AI4
AIN
73