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Page 23

| Figure 2-1 Basic components of a distribution transformer. |

| Currents are generated in the core by the alternating magnetic flux (or lines of force) as it cuts through the metal core. These currents, known as eddy currents, also create heat and contribute to the losses in a transformer. These are minimized by constructing the core of thin sheets or laminations, and by insulating adjacent laminations with insulating varnish (Fig. 2-3 on page 24). The laminations and varnish tend to present a high resistance path to these eddy currents, thereby reducing their magnitude, and the consequent losses. If these laminations are not properly secured, they will tend to vibrate contributing further to the noise or hum of a transformer. |

| The principal types of transformer construction are known as the core type and the shell type (Fig. 2-4 on page 24); both of these refer to the arrangement of the steel core with reference to the windings. In the core-type |

| Figure 2-2 Molecular motion during magnetic field reversal (hysteresis). |

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