If positive-sequence voltages are assumed and the Y- \(\Delta\) connection is considered, again with ideal transformers as in Problem 3.29, find the complex voltage gain \(C_{3}\).

(a) What would the gain be for a negative-sequence set?

(b) Comment on the complex power gain.

(c) When terminated in a symmetric Y-connected load, find the referred impedance \(Z_{L}^{\prime}\), the secondary impedance \(Z_{L}\) referred to primary (i.e., the per-phase driving-point impedance on the primary side), in terms of \(Z_{L}\) and the complex voltage gain \(C\).

Problem 3.29

Consider three ideal single-phase transformers (with a voltage gain of \(\eta\) ) put together as a \(\Delta-\Omega\) three-phase bank as shown in Figure 3.35. Assuming positive-sequence voltages for \(V_{a w}, V_{b n}\), and \(V_{c n}\), find \(V_{a^{\prime} n^{\prime}}, V_{b^{\prime} n^{\prime}}\), and \(V_{C^{\prime} n^{\prime}}\) in terms of \(V_{a n}, V_{b n}\), and \(V_{c n}\), respectively.

Transcribed Image Text:

a o bo Ica la m lab -O a' b'