In practical transformer the leakage reactance is an important fact to take in to consideration. This is because leakage reactance causes loss decreasing the transformer efficiency and disturbance to normal operation of transformer.

## What is Leakage reactance in transformer:

The magnitude of this reactance is a function of the number of turns in the windings, the current in the windings, the leakage field, and the geometry of the core and windings. The magnitude of the leakage reactance is usually in the range of 4 to 20% at the base rating of power transformers.

#### Calculation of leakage reactance

It is calculated by designers using the number of turns, the magnitudes of the current and the leakage field, and the geometry of the transformer. It is measured by short-circuiting one winding of the transformer and increasing the voltage on the other winding until rated current flows in the windings. This voltage divided by the rated winding voltage

The percent regulation can be determined using the following equation for inductive loads.

where

%Reg = percentage voltage drop across the resistance and the leakage reactance

%R = percentage resistance = (kW of load loss/kVA of transformer)

%x = percentage leakage reactance

Φ=angle corresponding to the power factor of the load.

For capacitance loads, change the sign of the sine terms.

Short URL to this post – http://goo.gl/J9tA5E