Toshiba Transmission & Distribution Systems Graduate Engineer Interview Questions, Process, and Tips

60 percent core and 40 percent aptitude

Q1. What are the tests done on a transformer
Ans. 
Tests done on a transformer include insulation resistance test, turns ratio test, winding resistance test, and load test.
• Insulation resistance test checks the insulation resistance between windings and between windings and ground.

• Turns ratio test measures the ratio of the number of turns in the primary winding to the number of turns in the secondary winding.

• Winding resistance test measures the resistance of each windin...read more
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Q2. Why CT and PT are used
Ans. 
CT and PT are used in electrical systems for measurement and protection purposes.
• CT (Current Transformer) is used to measure high currents and step them down to a manageable level for measurement and protection devices.

• PT (Potential Transformer) is used to measure high voltages and step them down to a safe level for measurement and protection devices.

• CTs and PTs provide isolation and safety by separating the high volta...read more
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Q3. What is the generation voltage in india
Ans. 
The generation voltage in India varies depending on the location and power plant.
• The voltage ranges from 110V to 440V depending on the location.

• The power plants generate electricity at different voltages.

• The national grid operates at a voltage of 400kV and 765kV.

• India has a mix of AC and DC power transmission systems.
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Q4. Why do we use high voltage for transmission?
Ans. 
High voltage is used for transmission to reduce power loss and increase efficiency.
• High voltage reduces the current required for a given amount of power, which reduces power loss due to resistance in the transmission lines.

• Lower current also means smaller conductors can be used, reducing material and installation costs.

• High voltage transmission is more efficient over long distances, reducing the need for additional pow...read more
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Q5. Which power plant is cheapest to install
Ans. 
Renewable energy power plants are generally cheaper to install than traditional fossil fuel power plants.
• Renewable energy power plants such as solar, wind, and hydroelectric are cheaper to install than traditional fossil fuel power plants.

• The cost of installation for renewable energy power plants has decreased significantly in recent years due to advancements in technology and increased demand.

• Fossil fuel power plants ...read more
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Q6. Why OC test done on LV side and SC test on HV side of Transformers
Ans. 
OC test is done on LV side to avoid high voltage on secondary side. SC test is done on HV side to avoid high current on primary side.
• LV side has lower voltage rating, hence safer for OC test

• HV side has higher current rating, hence suitable for SC test

• OC test checks insulation resistance and winding resistance

• SC test checks impedance and voltage regulation

• Example: A 100 MVA transformer with 220 kV HV and 33 kV LV rating
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