What is residual magnetism? Where is it important?

What is residual magnetism? Where is it important?
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1 Answer

Answer :

Residual magnetism is a property in which certain amount of excitation remains back in the conductor even after the removal of the magnets.
It is required as we need some magnetism to start off the generation before the field winding has power to produce the full field.
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Related questions

What is residual magnetism?*

Description : What is residual magnetism?*

Last Answer : Magnetism remaining in a Ferro magnetic material after the removal of magnetizing force.

What is the meaning of residual magnetism?

Description : What is the meaning of residual magnetism?

Last Answer : Residual magnetism is a property in which certain amount of excitation remains back in the conductor even after the removal of the magnets.

Indicate which of the following material does not retain magnetism permanently. (a) Soft iron (b) Stainless steel (e) Hardened steel (d) None of the above

Description : Indicate which of the following material does not retain magnetism permanently. (a) Soft iron (b) Stainless steel (e) Hardened steel (d) None of the above

Last Answer : (a) Soft iron

Materials subjected to rapid reversal of magnetism should have (a) large area oiB-H loop (b) high permeability and low hysteresis loss (c) high co-ercivity and high retentivity (d) high co-ercivity and low density

Description : Materials subjected to rapid reversal of magnetism should have (a) large area oiB-H loop (b) high permeability and low hysteresis loss (c) high co-ercivity and high retentivity (d) high co-ercivity and low density

Last Answer : (b) high permeability and low hysteresis loss

Voltage build up in an isolated induction generator depends on A. Capacitor bank value B. Residual magnetism of the rotor iron C. Residual magnetism of the stator iron a) A, B b) A, B, C c) B d) A, C

Description : Voltage build up in an isolated induction generator depends on A. Capacitor bank value B. Residual magnetism of the rotor iron C. Residual magnetism of the stator iron a) A, B b) A, B, C c) B d) A, C

Last Answer : Ans: A

If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of wood C. inject small amounts of CO2 into the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents

Description : If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of ... the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents

Last Answer : Answer: A

The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual magnetism C. kept warm by using strip or space heaters D. relieved of all capacitive charge by grounding the conductors

Description : The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual ... using strip or space heaters D. relieved of all capacitive charge by grounding the conductors

Last Answer : Answer: C

Which of the methods listed is used to start a AC generator turning? A. Residual magnetism remaining in the field poles. B. Residual magnetism remaining in the field coils. C. Residual magnetism remaining in the armature. D. Rotation by a mechanical prime mover.

Description : Which of the methods listed is used to start a AC generator turning? A. Residual magnetism remaining in the field poles. B. Residual magnetism remaining in the field coils. C. Residual magnetism remaining in the armature. D. Rotation by a mechanical prime mover.

Last Answer : Answer: D

In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded for 10 minutes to remove static charges. B. The transformer connections must be made as before with regard to the indicated polarity. C. The iron core of the transformer must be flashed to pre-magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.

Description : In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded ... magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.

Last Answer : Answer: B

One of the generator bearing shells is generally insulated from the end housing in order to prevent _____________. A. rapid brush wear B. residual magnetism leak off C. excessive field winding heat D. circulation of shaft currents

Description : One of the generator bearing shells is generally insulated from the end housing in order to prevent _____________. A. rapid brush wear B. residual magnetism leak off C. excessive field winding heat D. circulation of shaft currents

Last Answer : Answer: D

Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator to run at 10% of normal speed for 5 minutes C. running the generator at normal speed with the field rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field

Description : Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator ... rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field

Last Answer : Answer: D

If a magnetic controller contact fails to pick up when the operating coil is energized, one possible cause may be _______________. A. low spring pressure B. low voltage to the coil C. the residual magnetism of the contact faces D. dirty contact faces

Description : If a magnetic controller contact fails to pick up when the operating coil is energized, one possible cause may be _______________. A. low spring pressure B. low voltage to the coil C. the residual magnetism of the contact faces D. dirty contact faces

Last Answer : Answer: B

Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Description : Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Last Answer : Answer: D

The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings

Description : The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings

Last Answer : Answer: B

Residual magnetism in steel for magnets is increased by the addition of (A) Nickel (B) Cobalt (C) Tungsten (D) Chromium

Description : Residual magnetism in steel for magnets is increased by the addition of (A) Nickel (B) Cobalt (C) Tungsten (D) Chromium

Last Answer : (B) Cobalt

Addition of __________ to the steel helps in increasing the residual magnetism in steel used for making magnets. (A) Chromium (B) Nickel (C) Tungsten (D) Cobalt

Description : Addition of __________ to the steel helps in increasing the residual magnetism in steel used for making magnets. (A) Chromium (B) Nickel (C) Tungsten (D) Cobalt

Last Answer : (D) Cobalt

The magnetism left in the iron after exciting field has been removed is known as (a) permeance (b) residual magnetism (c) susceptance (d) reluctance

Description : The magnetism left in the iron after exciting field has been removed is known as (a) permeance (b) residual magnetism (c) susceptance (d) reluctance

Last Answer : (b) residual magnetism

If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be?

Description : If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be?

Last Answer : If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be zero.

In D.C. machines the residual magnetism is of the order of?

Last Answer : In D.C. machines the residual magnetism is of the order of 2 to 3 percent.

Which is the most important building block of electronic devices? (a) Diode (b) p-n junction (c) transistor (d) rectifier

Description : Which is the most important building block of electronic devices? (a) Diode (b) p-n junction (c) transistor (d) rectifier

Last Answer : b) p-n junction

An important port of a photocopier is: (a) Deflation plates (b) Toner (c) Charging electrode (d) Printed head

Description : An important port of a photocopier is: (a) Deflation plates (b) Toner (c) Charging electrode (d) Printed head

Last Answer : (b) Toner

An important part of inkjet printer is: (a) Deflection plates (b) Toner (c) Drum (d) None of these

Description : An important part of inkjet printer is: (a) Deflection plates (b) Toner (c) Drum (d) None of these

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Which of the two types of electron motion (orbital movement and electron spin) is more important in the explanation of magnetism?

Description : Which of the two types of electron motion (orbital movement and electron spin) is more important in the explanation of magnetism?

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5) An iron ring of mean circumference of 80 cm is uniformly wound with 500 turns of wire. Calculate the value of flux density that a current of 1 A would produce in the ring. Assume relative permeability 1400.

Description : Please ripley me due to emergency

Last Answer : To calculate the flux density in the ring, you need to use the following formula: B = (μ * I * N) / (2 * π * r) where: B is the flux density in the ring (in teslas) μ is the relative permeability ... 2 * π * 0.127 m) = 0.53 T So the flux density in the ring would be approximately 0.53 teslas.

Can you help me solve my electrical mystery?

Description : Can you help me solve my electrical mystery?

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Description : Air conditioning will not turn on, is it electrical?

Last Answer : Pull the Thermostat off the wall and see if it is connected correctly to the AC switch. There should be no dangling wires, and the post labeled for the AC should have an attached wire.

What is the speaker driving voltage of an amplifier?

Description : What is the speaker driving voltage of an amplifier?

Last Answer : I have to ask WHY? That said, Speakers and a light bulb are two different types of load, and the the lights will probably fry the output transistor.

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Description : Why is my Garbage disposal leaking water from the bottom?

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Last Answer : I’ve heard this rumor, and I too question it’s validity. I mean, if electricity can’t travel up a stream of urine (See mythbusters) I’m pretty sure it couldn’t travel through a shower stream. Perhaps through the drain? In either case, I’ve taken a shower in a storm before, and.. well, you see?

Electrical breaker box is buzzing-why??

Description : Electrical breaker box is buzzing-why??

Last Answer : No! Do not upgrade the breaker. The wire must also be upgraded if you do. Try plugging it in a different room. Is the problem still there?

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