You will need

- - transformer;
- - AC power source;
- tester;
- calculator.

Instruction

1

Take an ordinary transformer. It consists of two coils. Find the number of turns of coil N1 and N2, which are the basis of the transformer and connected to the magnetic circuit. Determine the coefficient

**of transformation**k. To do this, divide the number of turns of the primary coil N1, which is connected to the current source, the number of turns of the secondary coil N2 connects to load: k=N1/N2.2

Example. Winding of the transformer connected to the current source, has 200 turns and the other winding of 1200 turns. Determine the coefficient

**of transformation**and the type of the transformer. Find the primary and secondary windings. The primary is the one that is connected to the current source, it has 200 turns. The secondary winding is respectively 1200 turns. Calculate the coefficient**of transformation**according to the formula: k=N1/N2=200/1200=1/6≈0,167. Transformer increases.3

Measure electromotive force (EMF) on both windings of the transformer ε1 and ε2, if it is not possible to know the number of turns in them. To do this, connect the primary winding of the transformer to the power supply. This mode is called idle. With a tester find the voltage across the primary and secondary winding. It will be equal to the EMF of each winding. Keep in mind that energy losses due to the resistance of the windings are negligibly small. Calculate the rate

**of transformation**the ratio of the EMF of the primary and secondary winding: k= ε1/ε2.4

Example. The voltage across the primary winding after the connection to the source of current is 220 V. an open On the secondary winding voltage is 55 V. Find the coefficient

**of transformation**. The transformer is idling, so the voltage on the windings count is equal to the EMF. Calculate the coefficient**of transformation**according to the formula: k=ε1/ε2=220/55=4.5

Find the coefficient

**of transformation of the**working of the transformer when the secondary winding is attached to the user. Calculate it by dividing the current in the primary winding I1, the current I2 in the secondary winding. The current measure, adding sequentially windings tester, switched to the operation mode of the ammeter: k=I1/I2.Note

Transformer connect only to AC power source, otherwise it will not work and can deteriorate.

# Advice 2 : How to determine the transformation ratio

**The ratio**

**of transformation**is one of the fundamental parameters of any transformer. If this figure is unknown, it is possible to determine eksperimentalnim way.

Instruction

1

Prepare auxiliary transformer that develops on the secondary winding voltage of about 3 V. It can be, for example, filament winding of the transformer from any damaged device with vacuum-luminescent indicator. In any case do not short-circuit the coil.

2

To test the transformer with an ohmmeter or equivalent device, locate the winding with the least resistance. When measuring, pay attention to the difference even in the fractions of ohms. It contains the least number of turns. When measuring do not touch live parts to eliminate the impact of voltage of self-induction.

3

Apply voltage to 3V with an auxiliary transformer winding with the least number of turns specified above, through the fuse 0.25 A. First, connect the auxiliary transformer with the test, and then apply to auxiliary transformer power supply. His serve also through a fuse of the same amperage. Do not touch the elements of the primary circuit.

4

Parallel winding of the transformer with the least number of turns connect the AC voltmeter. Write down his testimony.

5

Start to connect the same voltmeter to the other windings of the transformer. If necessary, switch the limits. Remember that other windings can act high voltage. Each time write down the readings as well as the location of the conclusions of these windings. Avoid during measurements even momentary short circuits.

6

After finishing the experiment, unplug the auxiliary transformer, and then disassemble the installation.

7

To determine the coefficient

**of transformation**between any two windings of a transformer, divide the voltage on one of them on the voltage on the other. If desired, make a table of coefficients**transformation**for all combinations of its windings.