GE D90 Plus - Page 205

CHAPTER 7: PROTECTION GROUPED PROTECTION ELEMENTS
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL 195
Figure 173: Quadrilateral distance characteristic sample shapes
Transformer Voltage Connection
Range: None, Dy1, Dy3, Dy5, Dy7, Dy9, Dy11, Yd1, Yd3, Yd5, Yd7, Yd9, Yd11
Default: None
The phase distance elements can be applied to look through a three-phase delta-wye or
wye-delta power transformer. In addition, VTs and CTs can be located independently
from one another at different windings of the transformer. If the potential source is
located at the correct side of the transformer, set this value to “None.”
This setting specifies the location of the voltage source with respect to the involved
power transformer in the direction of the zone. The following figure illustrates the usage
of this setting. In section (a), zone 1 is looking through a transformer from the delta into
the wye winding. Therefore, the zone 1
Transformer Voltage Connection is set to “Dy11.”
In section (b), zone 4 is looking through a transformer from the wye into the delta
winding. Therefore, the zone 4
Transformer Voltage Connection is set to “Yd1”. The zone
is restricted by the potential point (location of the VTs) as illustrated in section (d).
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