Question

What is meant by transformer impedance?

Answer 1

Transformer impedance refers to the opposition a transformer presents to the flow of alternating current (AC). It's made up of two main parts:

1. Resistance (R): This is the real part of the impedance, which comes from the resistance of the transformer's windings (copper or aluminum wires). It causes power losses in the form of heat when current flows through it.
   

1. Reactance (X): This is the imaginary part of the impedance, caused by the inductive nature of the transformer. It resists changes in current and is responsible for the transformer’s ability to transfer energy at different frequencies.
   

So, the impedance of a transformer is a combination of these resistive and reactive components, which affects how the transformer performs in the circuit. It's typically expressed in ohms (Ω).

Transformer impedance is important because:

1. It affects the voltage drop across the transformer.
   

1. It determines how the transformer reacts to load changes.
   

1. It influences the short circuit current and fault levels in the system.
   

Impedance is often given as a percentage, which represents how much the impedance is in relation to the rated voltage and current of the transformer. For example, a transformer with 5% impedance means that the voltage drop due to the impedance will be 5% of the rated voltage under full-load conditions.