Slide 1
Changing magnetic flux couples the windings
A transformer uses changing magnetic flux, a measure of the magnetic field passing through a winding, to induce voltage in another winding.
It can change voltage levels without a rotating shaft.
More to Read
A magnetic core often guides the flux between windings. The core improves coupling, but winding insulation and geometry remain essential to how the device performs.
Slide 2
The turns ratio sets the ideal voltage ratio
For an ideal transformer, the voltage ratio follows the ratio of winding turns. More secondary turns produce a larger secondary voltage.
More to Read
A primary with 100 turns and secondary with 200 gives an ideal twofold voltage increase. Under load, real voltage also depends on winding resistance and magnetic leakage.
Slide 3
For the same power, higher voltage means lower current
An ideal transformer conserves power, so increasing voltage reduces the corresponding output current for the same transferred power.
More to Read
High-voltage transmission can reduce current for a given power. Since resistive line heating scales with current squared, this can reduce losses, while requiring insulation and equipment appropriate to the higher voltage.
Slide 4
Steady direct current does not keep changing the flux
After a switching transient, steady direct current creates no continuing change in flux. An ordinary transformer cannot continuously transform it in the usual way.
More to Read
Electronic converters can first switch a direct-current supply into a changing waveform. The transformer then operates on that changing signal, which is why a device powered by a battery may still contain one.
Slide 5
Real windings and cores still lose energy
Real transformers heat through electrical resistance and magnetic effects. Their design depends on frequency, loading and temperature limits.
More to Read
Thin insulated core laminations reduce some circulating-current losses in suitable designs. A transformer built for one frequency may overheat or saturate if used under incompatible conditions.
Sources
- Motors, Generators, and Transformers
OpenStax
- Batteries, Circuits, and Transformers
US Energy Information Administration