Important Interview Questions of Magnetic Circuits

1. Mention the types of Electrical machines.

There are three basic Rotating machine types, namely

1. The dc machines
2. The poly phase Synchronous machine (ac)
3. Poly and Single-phase Induction machine (ac)and a Stationary machine, namely Transformer

2. State Ohm’s law for Magnetic circuit

According to this, the product of the Magnetic flux passing through the Magnetic element and the Magnetic Material’s Reluctance equals the magneto motive force across the Magnetic element. It is provided by

MMF = Flux X Reluctance

3. Define leakage flux

Leakage flux is the flux Configuration in the airways Surrounding the Magnetic material.

4. Define Magnetic Reluctance

Magnetic reluctance is the resistance provided by the magnetic circuit to the magnetic flux path. Similar to electric resistance, it is.

5.  Draw the typical normal Magnetization curve of Ferromagnetic material.

6. What is Fringing?

Due to the reluctance of the air gap, the magnetic flux in the air gap of a machine exhibits non-uniform flux density. This is because the magnetic flux fringes out into nearby air paths. This phenomenon is known as the fringe effect.

7. State Stacking factor

The ratio of a magnetic core’s net cross sectional area to its gross cross sectional area is known as the stacking factor. Net cross sectional area will always be smaller than gross cross sectional area due to lamination. As a result, the stacking factor’s value is never greater than 1.

8. Mention some Magnetic materials

Alnicos, chromium steels, copper–nickel alloy, nickel, cobalt, tungsten and aluminium.

9. What is Magnetostriction?

When ferromagnetic materials are subjected to magnetizing mmf, these may undergo small changes in dimension; this phenomenon is known as magnetostriction.

10. Define Statically induced emf.

Although the flux through the coil doesn’t move, the coil’s position remains constant. Known as statically induced emf, the induced emf is produced.

11. Define Dynamically induced emf.

Flux density distribution remains constant and stationary but the coil move relative to it. The emf induced is known as dynamically induced emf.

12. State Fleming’s right hand rule.

Extend the thumb, fore and middle finger of the right hand so that they are mutually

perpendicular to each other. If the thumb represents the direction of movement of conductor and the fore finger the direction of magnetic flux, then the middle finger represents the direction of emf

13. State Fleming’s Left hand rule.

Extend the thumb, fore and middle finger of the right hand so that they are mutually perpendicular to each other. If the forefinger represents the direction of flux and the middle finger the direction of current, then the middle finger represents the direction of movement of conductor.

14. What are the core loss?

Hysteresis loss and eddy current loss.

15. Define Coercivity

It is the measure of mmf which, when applied to the magnetic circuit would reduce its flux density to zero, i.e., it demagnetizes the magnetic circuit.

These are some Important Interview Questions of Magnetic Circuits