Heat Generation in and Cooling of Transformers

Heat Generation in and Cooling of Transformers The losses in a transformer are small in relative terms, but they are appreciable in absolute terms, especially in large-size units. Therefore, a major task in transformer design is to provide for prop­er withdrawal of the heat generated in the core and coils to the sur­roundings. The task […]
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Multiwinding Transformers

Multiwinding Transformers In many electrical installations it is desired to have an intercon­nection between several circuits (or networks) operating at different voltage levels. Most conveniently this can be done with a multi wind­ing transformer which has one or several primary windings and sev­eral secondary windings. The simplest unit in this class is a three-­winding transformer […]
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Autotransformers

Autotransformers In power transmission it is sometimes necessary to interconnect electric networks whose rated voltages differ in a 2-to-1 ratio at most. An example is an interconnection of a 110-kV network and a 220-kV network. This form of interconnection is effected with the aid of a transformer or, to be more specific, an autotransformer ‘which […]
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Phase Displacement (Reference Phasor) Groups

Phase Displacement (Reference Phasor) Groups Under normal operating conditions, the primary and secondary voltages v1 and v2 are practically in phase with the respective cur­rents, il and i2, for the positive directions chosen in Fig.21. For the chosen positive directions of the load current iload and load volt­age vload it follows that iload = i2 […]
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The Short-Circuit Condition of a Transformer

The Short-Circuit Condition of a Transformer This condition may arise as a result of a fault fraught with grave consequences (overheating and break-down), or it may be produced for testing purposes in which case it is called the short-circuit (or load loss and impedance) test. The short-circuit test is carried out by short-circuiting the secon­dary […]
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