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TRANSFORMER TYPES

There are basically two transformer types .

  1. Step Down Transformer
  2. Step Up Transformer

Step Down Transformer

Step down transformers are used to step down heigh voltages i.e from 11000v to 220v or 110v and from 220v or 110v to 10, 12, 20 or 24 volts etc.

Because the same magnetic flux lines cut both coils of a transformer, the induced EMF in the secondary winding, is proportional to the number of turns on both the primary and secondary windings. If the number of turns on the secondary winding is less than the number of turns on the primary winding, then the secondary output voltage will be less than the primary input voltage. This type of transformer is called a step-down transformer and is illustrated in Figure.

Step Down Transformer

Example:

A transformer has 2660 turns on the primary side and 140 turns on the secondary side. If the primary voltage is 230 Volts AC, find the secondary voltage?

Solution

 

U1 / U2= N1 / N2

U2 = (U1 x N2) / N1

U2 = (230 x 140) / 2660

U2 = 12.10 Volts.

This is a step down transformer and is said to have a turns ratio of 2,660:140 or 19:1.

Step-Up Transformer

If the number of turns on the secondary winding of a transformer is greater than the number of turns on the primary winding, then the secondary output voltage will be greater than the primary input voltage. This type of transformer is called a step-up transformer and is illustrated in Figure.

Step Up Transformer

Example:

A transformer has 200 turns on the primary winding and 1200 turns on the secondary winding. If the primary voltage is 230VAC, what is the secondary voltage?

Solution

U1 / U2 = N1 / N2

U2 = (U1 x N2) / N1

U2 = (230 x 1200) / 200

U2 = 1380 Volts.

This is a step-up transformer and is said to have a turns ratio of 200:1200 or 1:6.