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Page 22

| 2 Transformer Construction.. |

| Principal Parts |

| The ordinary power supply transformer basically consists of two windings, insulated from each other, wound on a common core of magnetically suitable material such as iron or steel. One winding receives the energy from an ac source and is known as the primary winding. The other, which receives the energy by mutual inductance from the primary, delivers that energy to the load and is known as the secondary winding. The core provides a circuit or path for the easy flow of the magnetic lines of force or magentic flux. In addition to these, there are several other important parts which make up the practical power supply transformer: the enclosure, the terminals or bushings, and the coolant or cooling medium (Fig. 2-1). The requirements of all of these determine the kind of construction for the specific power supply transformer. |

| Cores |

| The construction of a transformer starts with the core. The material for this is chosen to afford its molecules the greatest ease in reversing their position as the ac magnetic field reverses its direction. The friction developed between these magnetic molecular particles as they reverse themselves creates heat, and this action causes a loss known as hysteresis (Fig. 2-2). This is minimized by using a special grade of heat-treated, grain-oriented silicon steel. These reversals of molecular particles also contribute to the noise or hum of a transformer. |

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