In the second example same the DUT as in the first example (YNd11 with turn fault on phase C)
is measured as Yd11. Because the neutral is not available, the 2293 can not measure each
phase individually. The measurement returns a combination of ratios of all three phases. The
system steps through the following procedure:
1. Connect to the DUT according the “Connection” column
2. Apply AC test voltage (in this case 25V
RMS
/ 55Hz)
3. Measure the “Ratio Raw” as U
HV
/ U
LV
4. Calculate the “Ratio Voltage” as “Ratio Raw” • “VR:RR” (2/√3 in this case)
5. Repeat 1-4 for the other two phases
6. Solve a system of equations generated by these three measurements to obtain
the true “Ratio Turn”
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