•
Solution 2
Figure 5-63shows use of the ICT Connection settings to correct for the phase shift introduced by the
transformer connection i.e. W1 ICT Connection is set to Yd9, -90° and W2 ICT Connection is set to Ydy0,
0°.
[dw_7SR5_function87Tsettingsexample11, 1, en_US]
Figure 5-63
AC Connections: Yd9, 90° Transformer – Standard Secondary Connections
An advantage of the approach above is that ‘standard’ secondary wiring connections are used.
The relay setting correspond to the power system vector relationship i.e. Yd9, 90°.
Relay instruments will indicate ’system’ quantities rather than transformer quantities.
Transformer with Primary Connections Crossed on One Winding
Reversing the connections on only 1 side of the transformer will reverse the phase sequence of the system.
For this arrangement W1 and W2 CT secondary wiring must be crossed over to replicate the crossovers on the
transformer primary connections – see Figure 5-64.
Protection and Automation Functions
5.22 87T Transformer Differential Protection
326 Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019
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