The coefficient of transformation is the main characteristic of the transformer. It shows as far as key parameters of electric current after it passes through this device change. When the transformation coefficient more than 1 – the transformer is called lowering if it is less – raising.
It is required to you
- - transformer;
- - source of alternating current;
- - tester;
- - calculator.
Instruction
1. Take the ordinary transformer. It consists of two coils. Find quantity of rounds of N1 and N2 coils which are a basis of the transformer and are connected by a magnetic conductor. Define coefficient of transformation of k. For this purpose divide quantity of rounds of primary N1 coil which is connected to a current source, on quantity of rounds of the secondary N2 coil to which loading is connected: k=N1/N2.
2. Example. The transformer winding connected to a current source has 200 rounds, and other winding of 1200 rounds. Define coefficient of transformation and type of the transformer. Find primary and secondary winding. Primary is that which is connected to a current source, it has 200 rounds. The secondary winding has, respectively, 1200 rounds. Calculate transformation coefficient by a formula: k=N1/N2=200/1200=1/6≈0.167. The transformer raising.
3. Measure the electromotive force (EMF) on both windings of the transformer ε1 and ε2 if there is no opportunity to learn quantity of rounds in them. For this purpose connect primary winding of the transformer to a current source. This mode is called idling. By means of a tester find tension on primary and secondary winding. It will be equal to the EMF of each of windings. Consider that losses of energy at the expense of resistance of windings are negligible. Calculate transformation coefficient through the relation of EMF of primary and secondary winding: k = ε1/ε2.
4. Example. Tension on primary winding after connection to a source of current is equal to 220 V. On the opened secondary winding tension is 55 V. Naydite transformation coefficient. The transformer idles therefore consider tension on windings equal EMFs. Calculate transformation coefficient by a formula: k=ε1/ε2=220/55=4.
5. Find coefficient of transformation of the working transformer when the consumer is attached to a secondary winding. Calculate it, having divided current in primary I1 to a winding, into current in secondary I2 to a winding. Measure current, attaching consistently to windings the tester switched to an operating mode of the ampermeter: k=I1/I2.