Table of Contents

**Losses In Transformers ; Hysteresis Loss, Eddy Current Loss, Efficiency**

#### We have discussed electrical transformer construction, working When it comes to efficiency of the transformer it is above 95%.In modern power transformers, we can get above 98% of efficiency. An electrical transformer is a static device, so no rotating losses or frictional, windage losses.So no mechanical losses occur in transformer.We consider only **electrical losses** in the transformer.Now read efficiency of transformer and losses in transformer below.

**Losses in Transformer**

#### As we no machine in this world is ideal.The transformer is also not an exception to this. There are two **types of losses in transformers** they are

(i) Core Losses Or Iron Losses

(ii) Copper Loss In Transformer

**(i) Core Losses Or Iron Losses in Transformer**

**Eddy current, Hysteresis losses are considered as core losses of transformer.**Core losses of transformer almost constant for a transformer after it is built for certain and frequency.Because eddy current loss and hysteresis loss depends on the magnetic properties, volume of the core which is used for the construction.As volume is fixed we can say **core losses or iron losses strictly depends only on frequency.**

**Hysteresis Loss in transformer**

#### Hysteresis losses occur due to reversal of magnetization in the transformer core.The magnetizing and demonstration curve of any material will not be same.Some loss happens due to cohesive force between magnetic atoms.

The hysteresis loss in transformer depends on the volume and grade of the iron, frequency of magnetic reversals and value of flux density. It can be given by, Steinmetz formula:

**W**

_{h}= ηB_{max}^{1.6}fV (watts)where, η = Steinmetz hysteresis constant

V = volume of the core in m^{3}

#### How to reduce Hysteresis Loss in Transformer?

#### We can reduce hysteresis losses by using **Cold Rolled Grain Oriented (CRGO) **Silicon Steel.In earlier days we used silicon steel as transformer core after that CRGO steel found less hysteresis constant.

**Eddy current loss in transformer**

**The transformer works only on alternating current** when AC current is supplied to the primary winding of transformer, it sets up alternating magnetizing flux. When this flux cuts the secondary winding, emf will be induced in it.This main flux also cuts the core of the transformer, As we know whenever flux cuts the magnetic material emf will induce in it.which will result in **small circulating currents** in them due to closed path of the core. This induced current is called as eddy current. Due to eddy currents, some energy will be dissipated in the form of heat.

** ****We= ηB²f²T (watts)**

**We ****∝ T**

#### where, η = Steinmetz hysteresis constant

#### T = Thickness of lamination in m