Transformer Interview Questions & Answers
Voltage regulation in a transformer reflects its capability to maintain a constant secondary voltage from no load to full load conditions, despite variations in load. It’s a critical measure of a transformer’s performance.
The transformer voltage regulation formula is based on the percentage change in secondary voltage from no load to full load conditions, highlighting the transformer’s efficiency in maintaining voltage stability.
Identifying whether a transformer is step-down or step-up can be determined by examining which side of the transformer voltage is applied and comparing the resistance of primary and secondary windings.
The supply voltage and power factor of a transformer are interrelated. Adjusting the voltage can impact the power factor, especially under load conditions, demonstrating the transformer’s influence on energy efficiency.
Increasing the frequency while maintaining a constant voltage in a transformer affects the magnetic flux and can lead to inefficiencies and potential over-fluxing, highlighting the balance needed for optimal transformer operation.
- Soft iron is preferred over steel in transformers due to its superior magnetic properties, including higher permeability and lower coercive force, which contribute to reduced core losses and improved efficiency.
Silica gel in power transformers is used to absorb moisture from air entering the conservator through the breather, protecting the oil and internal components from moisture-related issues.
Overheating in a transformer can be caused by exceeding its rated capacity or flux density, highlighting the importance of operating within specified limits for longevity and safety.
Understanding Transformers
Definition of Transformer
A transformer is an essential static device in electrical engineering, transferring electrical energy between two or more circuits through electromagnetic induction. It enables voltage level adjustments without changing the frequency, ensuring efficiency in power distribution.
Principle of Operation
The operation of a transformer is grounded in Faraday’s law of electromagnetic induction, utilizing mutual induction between windings to transfer energy and thus, maintaining power consistency across circuits.
Rating and Efficiency
The rating of a transformer reflects its ability to perform optimally under specified power and temperature conditions, typically expressed in kVA to account for various load types and power factors encountered in practical applications.
Power Factor Variations
The power factor in transformers shifts from low to nearly equivalent to the load’s power factor as the load increases, demonstrating its dynamic efficiency in energy transfer.
Core and Windings
The core of a transformer is designed to facilitate a low-reluctance path for magnetic flux, optimizing energy transfer, while the windings execute the transfer of energy via electromagnetic induction.
Magnetic Leakage Reduction
Minimizing magnetic leakage is crucial for maintaining transformer efficiency. Techniques include design optimizations such as core material selection and winding arrangements to enhance flux linkage.
CRGO Steel Core: A Deep Dive
Cold Rolled Grain Oriented (CRGO) steel is preferred for transformer cores due to its exceptional magnetic properties, significantly reducing energy losses and enhancing overall transformer performance.
Addressing Eddy Currents
The lamination of transformer cores into thin sheets is a strategic measure to increase resistance against eddy currents, thereby reducing unnecessary heating and energy loss.