Home
Class 12
PHYSICS
Large transformers, when used for some t...

Large transformers, when used for some time, become hot and are cooled by circulating oil. The heating of transformer is due to

A

1, 2 and 3 are correct

B

1 and 2 are correct

C

2 and 4 are correct

D

1 and 3 are correct

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

  • DUAL NATURE OF MATTER AND RADIATION

    DISHA|Exercise Physics|30 Videos

  • ELECTROMAGNETIC WAVES

    DISHA|Exercise Physics|29 Videos

Similar Questions

Explore conceptually related problems

When a Coolidge tube is operated for some time it becomes hot. Where does the heat come from?

Assertion : When a current flows in the coil of a transformer then its core becomes hot. Reason : The core of transformer is made of softiron.

Statement (A) : In high current low voltage windings of a transformer thick wire is used to minimize energy loss due to heat produced Statement (B) : The core of any transformer is laminated so as to reduce the erergy loss due to eddy currents.

After using for some time, big transformers get heated up. This is due to the fact that 1. the current produces heat in transformers 2. occurs in the hysteresis loss transformers 3. liquid used for cooling gets heated Select the correct answer using the code given below.

Read the following text and answer the following questions on the basis of the same: At power plant, a transformer increases the voltage of generated power by thousands of volts so that it can be sent of long distances through high-voltage transmission power lines. Transmission lines are bundles of wires that carry electric power from power plants to distant substations. At substations, transformers lower the voltage of incoming power to make it acceptable for high volume delivery to nearby end-users. Electricity is sent at extremely high voltage because it limits so-called line losses. Very good conductors of electricity also offer some resistance and this resistance becomes considerable over long distances causing considerable loss. At generating station, normally voltage is stepped up to around thousands of volts. Power losses increase with the square of current. Therefore, keeping voltage high current becomes low and the loss is minimized. Another option of minimizing loss is the use of wires of super-conducting material. Super-conducting materials are capable of conducting without resistance, they must be kept extremely cold, nearly absolute zero, and this requirement makes standard super-conducting materials impractical to use. However, recent advances in super-conducting materials have decreased cooling requirement. In Germany recently 1 km super-conducting cable have been installed connecting the generating station and the destination. It has eliminated the line loss and the cable is capable of sending five times more electricity than conventional cable. Using super-conducting cables Germany has also get rid of the need of costly transformers. Transformers generate waste heat when they are in operation and oil is the coolant of choice. It transfers the heat through convection to the transformer housing, which has cooling fins or radiators similar to heat exchangers on the outside. Flush point is a very important parameter of transformer oil. Flashpoint of an oil is the temperature at which the oil ignites spontaneously. This must be as high as possible (not less than 160^(@)C from the point of safety). Fire point is the temperature at which the oil flashes and continuously burns. This must be very high for the chosen oil (not less than 200^(@)C ). Flush point of an oil is

Read the following text and answer the following questions on the basis of the same: At power plant, a transformer increases the voltage of generated power by thousands of volts so that it can be sent of long distances through high-voltage transmission power lines. Transmission lines are bundles of wires that carry electric power from power plants to distant substations. At substations, transformers lower the voltage of incoming power to make it acceptable for high volume delivery to nearby end-users. Electricity is sent at extremely high voltage because it limits so-called line losses. Very good conductors of electricity also offer some resistance and this resistance becomes considerable over long distances causing considerable loss. At generating station, normally voltage is stepped up to around thousands of volts. Power losses increase with the square of current. Therefore, keeping voltage high current becomes low and the loss is minimized. Another option of minimizing loss is the use of wires of super-conducting material. Super-conducting materials are capable of conducting without resistance, they must be kept extremely cold, nearly absolute zero, and this requirement makes standard super-conducting materials impractical to use. However, recent advances in super-conducting materials have decreased cooling requirement. In Germany recently 1 km super-conducting cable have been installed connecting the generating station and the destination. It has eliminated the line loss and the cable is capable of sending five times more electricity than conventional cable. Using super-conducting cables Germany has also get rid of the need of costly transformers. Transformers generate waste heat when they are in operation and oil is the coolant of choice. It transfers the heat through convection to the transformer housing, which has cooling fins or radiators similar to heat exchangers on the outside. Flush point is a very important parameter of transformer oil. Flashpoint of an oil is the temperature at which the oil ignites spontaneously. This must be as high as possible (not less than 160^(@)C from the point of safety). Fire point is the temperature at which the oil flashes and continuously burns. This must be very high for the chosen oil (not less than 200^(@)C ). Oil transfers heat from transformer winding by the process of:

DISHA-ELECTROMAGNETIC INDUCTION-Physics
  1. A current of 5A is flowing at 220V in the primary coil of a transforme...

    Text Solution

    |

  2. An inductor (L = 100 mH), a resistor (R = 100Omega) and a battery (E =...

    Text Solution

    |

  3. which of ther following is constructed on the principle of electromagn...

    Text Solution

    |

  4. In the circuit, E = 10 volt, R(1) = 5.0 ohm, R(2) = 10 ohm and L = 5.0...

    Text Solution

    |

  5. Two inductors L(1) and L(2) are at a sufficient distance apart. Equiva...

    Text Solution

    |

  6. If the current in the primary coil is reduced from 3.0 ampere to zero ...

    Text Solution

    |

  7. A 50 Hz a.c. current of crest value 1A flows through the primary of a ...

    Text Solution

    |

  8. In an inductor of inductance L=100mH, a current of I=10A is flowing. T...

    Text Solution

    |

  9. A step up transformer has transformation ratio 5 : 3. What is voltage ...

    Text Solution

    |

  10. A step down transformer has turn ration 100//1. If secondary coil has ...

    Text Solution

    |

  11. A step-down transformer is used on a 1000 V line to deliver 20A at 120...

    Text Solution

    |

  12. Energy stored in an inductor is proportional to (i = current in the in...

    Text Solution

    |

  13. 1Voltage (r. m. s) in the secondary coil of a transformer depends upon...

    Text Solution

    |

  14. Large transformers, when used for some time, become hot and are cooled...

    Text Solution

    |

  15. In Fig. there is a conducting loop ABCDEF of resistance lambda per uni...

    Text Solution

    |

  16. In Fig. there is a conducting loop ABCDEF of resistance lambda per uni...

    Text Solution

    |

  17. In Fig. there is a conducting loop ABCDEF of resistance lambda per uni...

    Text Solution

    |

  18. Assertion: Soft iron is used as transformer core. Reason: Soft iron ...

    Text Solution

    |

  19. Assertion : An electric motor will have maximum efficiency when back e...

    Text Solution

    |

  20. Statement-1 : A transformer cannot work on dc supply. Statement-2 ...

    Text Solution

    |