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Appendix
12.9.7 Delta-Connected Windings
For delta-connected windings, R12, R23 and R31 cannot be measured directly
but calculated from the measured Ra, Rb and Rc values.
Ra = R1 + R2
Rb = R2 + R3
Rc = R3 + R1
Y connection without Neutral:
Rc - Rb + Ra = 2 R1
R1 = (Rc + Ra - Rb) / 2
Ra - Rc + Rb = 2 R2
R2 = (Ra + Rb - Rc) / 2
Rb - Ra + Rc = 2 R3
R3 = (Rb + Rc - Ra) / 2
Closed delta winding
R12 = R1 + R2 + (R1 x R2) / R3
R23 = R2 + R3 + (R2 x R3) / R1
R31 = R3 + R1 + (R3 x R1) / R2
Figure 12-15 Delta-connected windings
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