Saturday, July 4, 2009

Energy Losses in a Transformer

The energy loss of a transformer.
There are 4 main causes for energy loss in a transformer;
i. Heating effect in the coils. ( Your hand phone adapter become hot while charging !! )
Equation of heat energy , E = I x I x R x t
I = current
R = resistance
t = time

ii. Heating effect of eddy currents induced in the coil core.
The changing magnetic field causes the electrons in the soft iron core to circulate around as eddy currents. These eddy currents produce heating in the core and causes further loss of power.

iii. Hysteresis
Energy loss due to magnetization and demagnetization of the iron core of the transformer by alternating current. This transforms some energy into heat in the core.
Heat!?? energy loss again!

iv. Magnetic flux leakage
Flux leakage happens when some of the magnetic flux generated by the primary coil do not pass through the secondary coil.

How to improve the efficiency of a transformer?
To improved the efficiency of a transformer;
i. Thick copper wire of low resistance is used.
ii. The iron core is made of thin laminated sheets insulated from each other.
iii. Used soft iron core, which is able to be magnetization and demagnetization easily.
iv. Secondary coil is wound over the primary coil.

Solve problems involving transformers.
  • Efficiency of a transformer = ( useful output power/Input power ) x 100 %
  • Power = Current x voltage


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