Electrical Engineering » Notes » Transformer
1. A transformer consists of two coils, a primary winding and a secondary winding.
2. An AC voltage is put across the primary winding, inducing a voltage in the secondary winding.
3. Transformers allow an AC signal to be transferred from one circuit to another.
4. Transformers allow stepping up, stepping down, or passing the signal unchanged.
5. Transformers are designed to operate at certain frequencies.
6. Transformers are rated in volt-amperes (VA).
7. The turns ratio determines whether a transformer is used to step up, step down, or pass voltage unchanged.
turns ratio = NP/NS
8. The ratio of primary to secondary voltage is equal to the ratio of primary to secondary turns.
VP/VS = NP/NS
9. A transformer that produces a secondary voltage greater than its primary voltage is called a step-up transformer.
10. The turns ratio of a step-up transformer is always greater than 1.
11. A transformer that produces a secondary voltage less than its primary voltage is called a step-down transformer.
12. The turns ratio of a step-down transformer is always less than 1.
13. The amount the voltage is stepped up or down is determined by the turns ratio.
14. Transformer applications include : impedance matching, phase shifting, isolation, blocking DC while passing AC, and producing several signals at different voltage levels.
15. An isolation transformer passes the signal unchanged.
16. An isolation transformer is used to prevent electric shocks.
17. An autotransformer is used to step up or step down voltage.
18. An autotransformer is a special transformer that does not provide isolation.
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- Transformer » Exercise - 12. Which of the following is not a basic element of a transformer ? (a) core (b) primary winding (c) secondary winding (d) mutual flux
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