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Physics – Transformers and Generators

The principle how transformers and generators work is based on electromagnetic induction.

Generators generate current and transformers convert between current and voltage.

A generator is a machine which, with the help of magnetic induction, converts mechanical energy into electrical energy. This is possible by the revolution of coils in a magnetic field (a generator with exterior fields) or by the revolution of electromagnets around a fixed coil (a generator with internal fields). Generators usually generate alternating current, which may, using various devices, be converted into direct current. Generators work in the opposite manner as electrical motors, although an electrical motor can operate in the same way as a generator.

A transformer converts voltage into higher or lower voltages. Different voltage levels are used when generating electrical power, when transferring it, or when using it in a plant or in the home.

A transformer is made of two coils (primary-field and secondary-inductance), between which there is no electrical contact. If we allow a current to pass through the primary coil, a magnetic field is generated which changes but which maintains the same frequency. This succeeds in generating an alternating voltage in the secondary coil. An alternating current passes through a secondary coil when its electrical circuit is closed. The ratio or the size of the current then depends on the number of windings in the coil. If there are more windings in a secondary coil than in the relating primary coil, its voltage increases (and opposite in the other case). The greater the difference between the number of windings in the respective coils, the greater is the difference between their voltages.

The output of an electrical current cannot be changed by a transformer in that, if the voltage is increased, the quantity of current passing through it decreases because the product of both values must always remain the same. This effect is used when transferring electrical current. With electricity transferred over large differences, large voltages are transferred at very slow currents, which results in lowering any losses which may take place during the transfer.

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