Transformer losses
1.
Core loss or Iron loss
a.
Hysteresis loss in transformer:
Hysteresis loss is due to
reversal of magnetization in the transformer core.
This loss depends upon the
volume and grade of the iron, frequency of magnetic reversals and value of flux
density.
Steinmetz formula:
Wh= ηBmax1.6fV (watts)
where, η = Steinmetz hysteresis constant
V = volume of the core in m3
F = Frequency
Energy loss in a
transformer
(Eddy current in the
core )
b. Eddy current loss in transformer: In transformer, AC current is supplied to the primary winding which sets up alternating magnetizing flux. When this flux links with secondary winding, it produces induced emf in it. But some part of this flux also gets linked with other conducting parts like steel core or iron body or the transformer, which will result in induced emf in those parts, causing small circulating current in them. This current is called as eddy current. Due to these eddy currents, some energy will be dissipated in the form of heat.
·
Ke – coefficient of eddy current.
Its value depends upon the nature of magnetic material like volume and
resistivity of core material, the thickness of laminations
·
Bm – maximum value of flux density
in wb/m2
·
t – thickness of lamination in meters
·
F – frequency of reversal of the magnetic field in
Hz
·
V – the volume of magnetic material in m3
2.
Copper loss:
Copper loss is also called ohm loss; copper loss is also called variable
loss
Because if temperature increasing then winding resistance also increasing
That causes I2R loss also increase.
Copper loss is
due to ohmic resistance of the transformer windings. Copper loss for the
primary winding is I12R1 and for secondary winding is I22R2. Where, I1 and I2 are current in primary and secondary winding
respectively, R1 and R2 are the resistances of primary and secondary
winding respectively.
3.
Open circuit test
4.
Short circuit Test
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