Home
Class 11
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

heating effect of current alone

B

hysteresis loss alone

C

both the hysteresis loss and heating effect of current

D

none of the above

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

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-ALTERNATING CURRENT-PHYSICS
  1. A bulb is rated at 100V, 100W. It can be treated as a resistor. Find o...

    Text Solution

    |

  2. An ac source of angular frequency omega is fed across a resistor R and...

    Text Solution

    |

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

    Text Solution

    |

  4. An inductor of inductance L = 400 mH and resistors of resistance R(1) ...

    Text Solution

    |

  5. An ideal coil of 10H is connected in series with a resistance of 5(Ome...

    Text Solution

    |

  6. In an A.C. circuit, the current flowing in inductance is I = 5 sin (10...

    Text Solution

    |

  7. In an oscillating LC circuit the maximum charge on the capacitor is Q....

    Text Solution

    |

  8. A fully charged capacitor C with initial charge q(0) is connected to a...

    Text Solution

    |

  9. For an LCR series circuit with an aac source of angular frequency omeg...

    Text Solution

    |

  10. The rms value of potential difference V shown in the figure is

    Text Solution

    |

  11. Which of the following statements is/are incorrect?

    Text Solution

    |

  12. A lamp consumes only 50% of peak power in an a.c. circuit. What is the...

    Text Solution

    |

  13. A step down transformer reduces 220 V to 110 V. The primary draws 5 am...

    Text Solution

    |

  14. The voltage time (V-t) graph for triangular wave having peak value V(0...

    Text Solution

    |

  15. The tuning circuit of a radio receiver has a resistance of 50Omega , a...

    Text Solution

    |

  16. In an alternating current circuit in which an inductance and capacitan...

    Text Solution

    |

  17. A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz f...

    Text Solution

    |

  18. In the figure shown, three AC voltmeters have been connected. At reson...

    Text Solution

    |

  19. A.C. power is transmitted from a power house at a high voltage as

    Text Solution

    |

  20. A transformer has an efficiency of 80%. It works at 4 kW and 100 V. If...

    Text Solution

    |