We know that A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. A varying current in one coil of the transformer produces a varying magnetic field, which in turn induces a voltage in a second coil. Power can be transferred between the two coils through the magnetic field, without a metallic connection between the two circuits. We also know that the frequency of a transformer is almost constant. My question is that how Transformer Flux/ frequency remains constant? And is there any other device which can change the input frequency of a transformer?
Hi Eklas Hossain,
transformers don't have a frequency of their own. Generally, the ratio of the H field in the core to the B field in the core depends on the field strength; the H field depends on the current in the coils, the voltage induced in the coils depends on the changing of the B field. So - except for transformers without any ferromagnetic core - the transfer function of transformers isn't exactly linear. Consequently, if we apply voltage of a single frequency at the input, the frequency spectrum of the output voltage consists of the input frequency plus integer multiples of this frequency = harmonics. Due to symmetry, usually there are only the odd harmonics, e. g. base frequeny = 50 Hz, harmonics of 150 Hz, 250 Hz, and so on, with decreasing power.
Neglecting the harmonics, the reason we usually get a constant frequency at the output of line transformers is that the frequency on the power line is being controlled very tightly at the power plants. A counter example would be a transformer in a sound amplifier: You can input a frequency sweep from, say, 20 Hz to 20 kHz, and - apart from the harmonics - the same sweep comes out.
There are frequency converters which rectify the line voltage and generate a nearly sinusoidal voltage of a variable frequency, e. g. for running AC motors at variable speed. But usually, the motor is directly connected to the output of a frequency converter, without the introduction of a transformer.
In addition to what is mentioned above, non-linear load connected to the transformer, saturation of the flux in the core of the transformer, the inrush current (at excitation/ or due to any switching) etc. also alter the frequency of operation of the transformer. This means that external factors associated with the primary and secondary sides of the transformer and internal factors such as its iron and copper content and construct give rise to harmonics to tamper with the fundamental frequency.
- Badges
- Science topic
- Similar topics
- Biological Science
- Bioecology
- Systems Ecology
- Landscape Ecology
- Connectivity