So, no-load voltage = E2 volts
Full load voltage: It is the secondary terminal voltage of transformer when a rated load is connected to the transformer. We will denote it by V2.
Definition of Voltage Regulation of Transformer
The voltage regulation of transformer is defined as the change in secondary terminal voltage (V2) from no-load to full load at constant primary voltage and temperature. It is expressed as a percentage of the secondary no-load voltage.
Mathematically, % Regulation of transformer = (E2 – V2) x 100 / E2
When a transformer is loaded a voltage drop in primary and secondary impedances of transformer takes place. As the load current increases, this voltage drop will increase. This will reduce the secondary terminal voltage V2. The ideal value of voltage regulation of transformer is 0%.
The approximate expression for the total voltage drop (E2 – V2) in a transformer as referred to secondary is given by
R02 = equivalent resistance of transformer referred to secondary
X02 = equivalent reactance of transformer referred to secondary
R01 = equivalent resistance of transformer referred to primary
X01 = equivalent resistance of transformer referred to primary
Here it has been assumed that φ1 = φ2 = φ.
The positive sign is used for a lagging power factor and the negative sign for a leading power factor.
It is clear from the above expressions regulation of transformer does not depend only on the magnitude of load current. But it also depends on the type of load. The transformer regulation is positive for the resistive and inductive loads but it can be negative for the capacitive loads.
We can determine the values of R01, X01, R02, X02 of a transformer from short circuit test and calculate percentage regulation of transformer.
- Single Phase Transformer Working Principle
- Ideal Transformer on No Load
- Construction of Three Phase Transformer
- Types of Transformers
- Equivalent Resistance and Reactance of Transformer
- Equivalent Circuit of Single Phase Transformer
- Power Loss in a Transformer
- Open Circuit Test of Single Phase Transformer
- Short Circuit Test on Single Phase Transformer
- Transformer Efficiency
- Instrument Transformers
- Polarity of Transformer Windings
- Significance of Vector Group of Transformer
- Buchholz Relay Construction | Working
- Why current transformer secondary should not be opened