The armature core of a DC machine is laminated to minimize

Electrical Engineering XYZ MCQs

The armature core of a DC machine is laminated to minimize:

  1. Mechanical loss
  2. Temperature rise
  3. Hysteresis loss
  4. Eddy-current loss

Correct answer: 4. Eddy-current loss

Explanation: The correct answer is “Eddy-current loss.”

DC machines, like many electrical machines, have an armature core that is typically constructed using laminations. Laminating the core involves stacking thin sheets of ferromagnetic material and insulating them from each other. This lamination process is done to minimize eddy-current losses.

Eddy currents are circulating currents induced within the conductive material, in this case, the armature core, when it is exposed to changing magnetic fields. These currents lead to energy losses in the form of heat, which can be detrimental to the efficiency and performance of the machine.

By laminating the core, the electrical conductivity within the core is significantly reduced, effectively minimizing the generation of eddy currents and hence reducing the associated energy losses. This helps in improving the efficiency of the DC machine.

The other options:

  1. Mechanical loss: Laminating the armature core does not directly address mechanical losses in the machine, which typically occur due to friction and windage losses.
  2. Temperature rise: While laminating the core can indirectly contribute to reducing temperature rise by minimizing energy losses, it is not the primary reason for lamination.
  3. Hysteresis loss: Hysteresis loss occurs due to the reversal of magnetization in the core material and is mitigated through the use of materials with low hysteresis loss properties, but laminating the core primarily addresses eddy-current losses rather than hysteresis losses.

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