In the modern power system, a transformer is a vital piece of equipment. With the continuous growth of power demand and the change of grid load, we are faced with a common and critical question: how to effectively adjust the output voltage of the transformer to meet different power needs? Voltage regulation has become a hot topic in the power industry, and this article will take you to understand the voltage regulation method of transformers and the related factors that affect transformer voltage regulation.
What is voltage regulation in a transformer?
The voltage regulation of a transformer is defined as the percentage change in the secondary voltage of a transformer from no load to full load. In other words, transformer voltage regulation describes the ability of a transformer to provide a constant voltage from no load to full load. When the input power supply is constant, the secondary voltage of the transformer should not vary with the load. A transformer can be seen as a voltage source, and the variation of the secondary terminal voltage from no-load to full-load depends on the voltage drop in the transformer windings.
When current flows through a transformer, a voltage drop occurs due to the reactance and resistance of the transformer. The change in the secondary output voltage of a transformer from no-load to full-load is called the voltage regulation of the transformer.
Transformer voltage regulation formula
The voltage regulation of the transformer shows how well the transformer maintains a constant secondary output voltage from no-load to full-load when the primary voltage is constant.
Transformer Voltage Regulation Percentage Formula:
VN: Voltage at no load, VF: Voltage at full load.
The secondary output voltage decreases as the current flowing through the transformer increases. This happens due to the voltage drop in the windings of the transformer. The secondary output voltage at full load is always smaller than the output voltage at no load. The smaller the voltage difference between no-load and full-load state, the better the regulation effect of the transformer.
Example of voltage regulation.
The transformer's secondary output voltage is 220 volts at no load. When the transformer load reaches its full load current capacity, the secondary voltage is reduced from 220 volts to 210 volts. The voltage drop of the secondary output voltage from no-load to full-load = 10V.
If the transformer is loaded to its full load current capacity, the secondary voltage is reduced from 220 volts to 215 volts. In this case, the modulation rate of the transformer is 232%。The % regulation of the transformer should be as small as possible to have an almost constant secondary output voltage. In addition, when the regulation of the transformer is improved, the copper loss is also reduced.
What Factors Affect Transformer Voltage Regulation?
The following factors affect the voltage regulation of a transformer.
Resistance per phase:The resistance of the primary and secondary windings causes a voltage drop, and the greater the resistance, the greater the voltage drop. Transformers with higher primary and secondary resistance have poor voltage regulation.
Reactance per phase: The reactance of the primary and secondary windings causes a voltage drop. The greater the reactance, the greater the voltage drop. Transformers with higher primary and secondary reactances have poor voltage regulation.
Leakage flux: If the leakage flux is high, the leakage reactance XL increases, which increases the IAXL voltage drop. As a result, the ability to regulate pressure becomes very poor.
The magnitude of the secondary load current: If the load current increases, the IARA and IAXL voltage drops will increase. As a result, the voltage at the terminals drops, which makes the regulation poor.
Load power factor: The load power factor also affects the voltage regulation of the transformer. The hysteresis power factor requires more current and results in a greater voltage drop in the transformer windings. As a result, the voltage regulation of the transformer decreases. The leading power factor increases the secondary voltage of the transformer, which improves the regulation of the transformer.
With the progress of science and technology and the development of the power industry, the research and innovation of transformer voltage regulation technology is constantly advancing. The emergence and application of various voltage regulation methods enable us to meet the power needs of different fields more flexibly and improve the stability and reliability of the power system. In the future, we can expect the emergence of more intelligent voltage regulation solutions to bring greater benefits and convenience to the power industry.
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