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Page 83

| Figure 5-16 Polarity of three-phase transformer, showing phase displacement. (A) Zero degree phase displacement. (B) 180° phase displacement. |

| Figure 5-17 30° lead of wye side to delta side. |

| Figure 5-18 30° lag of wye side to delta side. |

| Other Connections |

| Some transformer connections used less frequently or for special purposes are described below. (Refer to Chap. 1, Fig. 1-17.) |

| Parallel Connection: Single-Phase |

| The two transformers connected in parallel (Fig. 5-19 on page 84) should preferably have the same characteristics. They should not only have the same voltage ratings and ratio of transformation, but preferably should also have the same impedance and the same polarity. If the impedances are not fairly close together, the load will not divide equally between them and one unit will reach its limit before the other thus reducing the capacity available from the other unit. |

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