Uttar Pradesh Power Corporation Electrical Engineer Interview Questions and Answers

Q1. What is working principle of transformer
Ans. 
A transformer operates on electromagnetic induction to transfer electrical energy between circuits at different voltage levels.
• Consists of primary and secondary coils wound around a magnetic core.

• Works on the principle of Faraday's law of electromagnetic induction.

• When alternating current flows through the primary coil, it creates a magnetic field.

• This magnetic field induces a voltage in the secondary coil.

• Transformers...read more
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Q2. What's efficiency of transformer
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The efficiency of a transformer measures how effectively it converts input power to output power, typically expressed as a percentage.
• Efficiency is calculated as (Output Power / Input Power) x 100%.

• Typical transformer efficiencies range from 95% to 99%.

• Higher efficiency reduces energy losses, making transformers more economical.

• Example: A transformer with 98% efficiency means 98% of input power is converted to output p...read more
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Q3. Types of generating power plants
Ans. 
Power plants generate electricity using various energy sources, including fossil fuels, nuclear, and renewables.
• Thermal Power Plants: Use fossil fuels like coal, oil, or natural gas (e.g., coal-fired plants).

• Nuclear Power Plants: Generate electricity through nuclear fission (e.g., plants using uranium).

• Hydroelectric Power Plants: Utilize flowing water to generate power (e.g., Hoover Dam).

• Wind Power Plants: Harness wind...read more
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Q4. What is hybrid system
Ans. 
A hybrid system combines different technologies or methodologies to leverage their strengths for improved performance and flexibility.
• Hybrid systems can integrate both analog and digital components, such as in hybrid cars that use both electric and gasoline engines.

• In computing, hybrid systems may refer to cloud computing models that combine public and private clouds for enhanced scalability and security.

• In control sys...read more
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Q5. Types of transformer
Ans. 
Transformers are electrical devices that transfer energy between circuits through electromagnetic induction, with various types for different applications.
• Step-up Transformer: Increases voltage, used in power transmission.

• Step-down Transformer: Decreases voltage, used in power distribution.

• Isolation Transformer: Provides electrical isolation, used in sensitive equipment.

• Auto Transformer: Has a single winding, used for ...read more
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Q6. What's central inverter
Ans. 
A central inverter converts DC electricity from solar panels into AC electricity for grid use or consumption.
• Central inverters are commonly used in large-scale solar power plants.

• They are more efficient for larger installations compared to string inverters.

• Examples include the SMA Sunny Central and ABB PVS series.

• Central inverters typically require more space and are installed in dedicated areas.

• They can manage multipl...read more
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Q1. How to protect transformer and what is VFD???
Ans. 
To protect a transformer, measures such as overcurrent protection, temperature monitoring, and proper grounding should be implemented. VFD stands for Variable Frequency Drive, a device used to control the speed of an electric motor.
• Implement overcurrent protection to prevent excessive current flow through the transformer.

• Monitor the temperature of the transformer using temperature sensors to prevent overheating.

• Ensure ...read more
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Q1. Previous company related
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Q1. What is CT, PT and different?
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Q1. Current company CTC
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Q1. Salary discuss and other accommodation
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Q1. What is buchholz relay in transformer.
Ans. 
A Buchholz relay is a safety device used in oil-filled transformers to detect faults and prevent damage.
• Monitors gas accumulation and oil flow in transformers.

• Triggers alarms or circuit breakers during faults.

• Commonly used in large power transformers.

• Example: Detects overheating or short circuits.

• Helps in preventing catastrophic failures.
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Q2. Explain kvl ans kcl
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KVL and KCL are fundamental laws in electrical engineering governing voltage and current in circuits.
• KVL (Kirchhoff's Voltage Law) states that the sum of all voltages around a closed loop equals zero.

• Example of KVL: In a series circuit with a 12V battery and two resistors (4Ω and 8Ω), the voltage drop across the resistors must equal 12V.

• KCL (Kirchhoff's Current Law) states that the sum of currents entering a junction e...read more
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Q1. Electrical question panel breaker HT breaker models HD panel LT breaker LT model circuit diagram motor relay contractor wiring hoist faster activator
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Q2. Electrical se sambandhit any question
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