Bissoy.com
Doctors Medicines MCQs Q&A

The laminated cores are used in transformers to reduce:

The laminated cores are used in transformers to reduce: Correct Answer Eddy current losses

CONCEPT:

Eddy current:

  • When a changing magnetic flux is applied to a bulk piece of conducting material then circulating currents called eddy currents are induced in the material.
  • Because the resistance of the bulk conductor is usually low, eddy currents often have large magnitudes and heat up the conductor.
  • These are circulating currents like eddies in the water.
  • The experimental concept was given by Focault hence also named “Focault current”.
  • The production of eddy currents in a metallic block leads to the loss of electric energy in the form of heat.
  • Eddy currents are undesirable in the metallic cores of transformers, electric motors, and other such devices in which a coil is to be wound over a metallic core since they heat up the core and dissipate electrical energy in the form of heat.
  • Eddy currents are minimized by using laminations of metal to make a metal core. The laminations are separated by an insulating material like lacquer.
  • Eddy currents are used to advantage in certain applications like:
    1. Magnetic braking in trains
    2. Electromagnetic damping
    3. Induction furnace
    4. Electric power meters


EXPLANATION:

  • Eddy currents are undesirable in the metallic cores of transformers, electric motors, and other such devices in which a coil is to be wound over a metallic core since they heat up the core and dissipate electrical energy in the form of heat.
  • Eddy currents are minimized by using laminations of metal to make a metal core. The laminations are separated by an insulating material like lacquer. Hence, option 3 is correct.

Related Questions

Consider the following statements regarding parallel connection of 3-phase transformers: 1. The secondaries of all transformers must have the same phase sequence. 2. The phase displacement between primary and secondary line voltages must be the same for all transformers which are to be operated in parallel. 3. The primaries of all transformers must have the same magnitude of line voltage. Which of the above statements are correct?
Laminated cores, in electrical machines, are used to reduce
After using for some time, big transformers get heated up. This is due to the fact that
1. current produces heat in the transformers.
2. hysteresis loss occurs in the transformers.
3. liquid used for cooling gets heated.
Select the correct answer:
Consider the following given statements about auto-transformers and choose the one which is/are correct. 1. Auto-transformers require less copper as compared to a conventional,2 winding transformer of the same capacity. 2. Auto-transformers provide isolation between the primary and secondary windings. 3. Auto- transformer has less leakage reactance as compared to the conventional, 2 winding transformer of the same capacity.
The core used in transformers and other electromagnetic device is laminated to
For small cores mass production, dielectric core bakers can be preferred over continuous type ovens used for baking cores.
For the removal of cores from the moulding box, caustic bath can be used which is very fast in processing the large and complex cores.
In permanent mould casting method, metallic cores are mainly used instead of sand cores.
After preparation of cores, cores on the core plates are sent for what?
The process of making green sand cores generally consumes much time as compared to that of dry sand cores.