Question

Make circuit diagrams for each of the objectives:

-tTo observe the input voltage and excitation current waveforms and the hysteresis loop resultingfrom the two waveformsof an unloaded transformer, transformer harmonic components, and tomeasure the power supplied to and power factor of the transformer.

also

-To observe the current waveform and the harmonics of a series lamp-diode circuit, and measure the power supplied to and power factor of the circuit.

Answer 1

When the transformer is operating at no load, the secondary winding is open circuited, which means there is no load on the secondary side of the transformer and, therefore, current in the secondary will be zero, while primary winding carries a small current I₀ called no load current which is 2 to 10% of the rated current. This current is responsible for supplying the iron losses (hysteresis and eddy current losses) in the core and a very small amount of copper losses in the primary winding. The angle of lag depends upon the losses in the transformer. The power factor is very low and varies from 0.1 to 0.15.

?Harmonic components of a three phase transformer:-

For power factor measurement the following circuit is used:-