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What is difference between residual magnetism and retentivity?
Residual magnetism and remanence are the same thing. The term residual magnetism is often used in engineering applications. Both terms describe the magnetization, and measure of that magnetism, left behind in a ferromagnetic material after the external magnetic field is removed.
What is the reason for the presence of residual magnetism in the field poles?
I'm not quite sure what you're asking, but the reason that there is magnetism at the poles has to do with the fact that magnetic field vector lines have no beginning or end, which is described mathematically through Maxwell's equations; specifically through Gauss' law for magnetism which states that the divergence of a magnetic field is 0, or ∇ ● B = 0. Divergence is a term meaning how much of something is exiting an enclosed surface. Since the divergence of a magnetic field is zero, there must be, always, the exact same amount of magnetic field exiting a surface as entering it, leaving the net divergence as 0.Thus, a magnetic field vector line has to "exit" from somewhere and loop around to "enter" somewhere else, and these two "somewheres" have to be connected (like a circuit). We call these two "somewheres" the magnetic poles.
Does a generator slowly lose its residual magnetism with time?
no coz a intilization is required by every componentAnswerYes, it can but, fortunately, it only happens occasionally. When this happens, it's necessary to demagnetise the field poles by passing an external d.c. current through the field windings. This process is known as 'flashing the field'.
What is the difference between magnetism and electricity?
The difference between electricity and magnetism is that you must be in the same frame of reference as the electric field to experience electricity, because all that magnetism is, is electricity moving relative to you.Although they are two different forms of energy, you can use magnetism to create electricity and you can use magnetism to create electricity.Electricity is the flow of energy or current through a metallic substance. Magnetism is the attraction of the metallic molecules in a solid or substance.
What is the sure test of magnetism?
The sure test of magnetism is the ability of a material to attract iron or other magnetic materials. If a material attracts iron, it is considered to be magnetic.
What is difference between residual magnetism and retentivity?
Residual magnetism and remanence are the same thing. The term residual magnetism is often used in engineering applications. Both terms describe the magnetization, and measure of that magnetism, left behind in a ferromagnetic material after the external magnetic field is removed.
Can a shunt motor be started without residual magnetism?
Yes. The field is provided by the shunt windings, which are connected in parallel with the supply. You may be confusing a motor with a generator, as you cannot start a shunt generatorwithout residual magnetism.
The flux density that remains when the magnetizing force is removed is called?
residual magnetism
What is residual magnetisim?
It depends on the context in which you are referring to it, but basically Residual Magnetism is that magnetism remaining in the core of an electromagnet after the coil current is removed. In the widest use of the term, it could be used to refer to that magnetism left in a magnetically susceptible substance when it cools past its Curie point, (paleomagnetism is an example of this).
How initially voltage build up in an alternator by residual magnetism?
The residual flux will help the phenomenon of changing flux. So that emf generation takes place.
If a selfexcited generator has lost all of its residual magnetism can it build up an output voltage?
yes
What is magnetism on Mars?
The magnetic field on Mars is only residual, it collapsed many eons ago.
For a 3 phase alternator why there is an AC voltage generated in the absence DC excitation?
due to residual magnetism
Is a36 steel magnetic?
A36 is paramagnetic. It is fairly good conductor of magnetic field, and it will be atracted to magnets strongly. As far as residual magnetism (can it be magnetized) I don't know for sure. I know you can not make usefully strong magnets out of A36 material, but it may have some residual magnetism.
What is residualmagnetism?
The retained magnetic flux of the material, even after the removal of the external magnetizing force is known as residual magnetism.
Why dc shunt generator can not induce any voltage with rated speed?
Two things could have occurred. (1) wrong direction of rotation causing loss of residual magnetism or (2) loss of residual magnetism over long period of no use. can be remedied by "flashing" the shunt field winding howlumf
What is meant by flashing a field in excitation?
A generator needs to have residual magnetism in its field coils to start the generation of electricity. A generator that has not been run in a long time will loose this magnetism. Because the field voltage is a DC supply, a battery across the field wiring will energize the coils instantaneously. Doing this several times will cause sparking when the contact to the battery is broken, hence the flash. This intermittent energizing and de-energizing will bring the residual magnetism back into the field coils. When the generator is started, the voltage output should rise to its normal level. If it does the magnetizing of the field coils to bring back the residual magnetism will have worked.
