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Page 84

| Figure 5-19 Parallel connection of two single-phase transformers to a 3-wire circuit. |

| In the occasion where it may be necessary to connect transformers with different polarities, the corresponding numbered terminals should be connected together rather than the terminals in the same physical position. If this is not done, the transformers maybe short-circuited and the units damaged. |

| On occasion, the transformers to be connected in parallel may not be located alongside each other, but may be located at locations remote from and out of sight of each other. Such connections are referred to as banking of the transformer secondaries, and are sometimes used to correct or improve local load and voltage conditions. The same considerations and precautions should be observed as for those located together. An added precaution is necessary, that the phase relation of the primary supply in the locations remote from each other be the same, otherwise short-circuits damaging the units will result. |

| Phase Transformation: Three-Phase/Two-Phase.. |

| Often, it may be desirable and economical to supply a two-phase load from a three-phase source, or vice versa. There are several ways this may be done, but two of particular commercial importance are the Scott connection and the wye to two-phase connection. |

| Scott Connection |

| In this connection (Fig. 5-20), single-phase transformers having 50 percent and 86.6 percent taps on the three-phase side are required. One transformer, called the MAIN transformer is connected between two of the three-phase wires; the other, called the TEASER is connected between the third phase wire and its 86.6 percent tap is connected to the 50 percent tap of the MAIN transformer. |

| The two-phase side is shown as a four-wire circuit, but may also be three-wire or five-wire. Conductors a-2 and b-1 can be connected together or |

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