answersLogoWhite

0

Usually the term "residual magnetism" is used in referring to the weak, leftover magnetic force remaining in field coil poles in generators. These generators can be the automotive type, but can also be any other type of generator in which a Direct Current is used in a series of field windings wrapped around field cores to produce magnetic fields around a rotating armature with the purpose of producing electricity from mechanical motion (the rotating armature).

The field winding poles/cores are made of iron, and after the generator has been run a few seconds under load, will retain a weak magnetic field even after the generator has been shut down. This is the "residual magnetism". The majority of older-design generators depend upon this weak, leftover field to restart the voltage produced in the armature, rather than the voltage regulator depending upon a battery to restart the generator field magnetism.

Residual magnetism gets weaker over time; the time depends in part on the quality of the field pole piece and and how strong the current applied to the field coils was at the time the generator was stopped.

To temporarily restore the residual magnetic field, current will need to be applied to the field circuit BRIEFLY; completely disconnecting the generator will be required. Connecting a 6 volt "lantern battery" in the proper polarity across the field winding circuits for a few seconds will establish a residual magnetic field in each field coil/windingzperiodz Proper polarity is critical: backwards polarity will create backwards residual magnetic fields, and the generator will produce backwards-polarity electricity when the armature is spun.

User Avatar

Wiki User

15y ago

What else can I help you with?

Related Questions

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 residual magnetism?

Residual magnetism is the magnetism that remains in a material even after an external magnetic field is removed. This phenomenon is commonly observed in magnetic materials such as iron and steel after they have been magnetized. Residual magnetism allows these materials to retain some magnetization and can be useful in applications such as magnetic memory storage devices.


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.


What is the best treatment to reduce residual fibrosis?

acetylcysteine