Ответ на вопрос по английскому языку №19506: One important difference between alternating- and direct-current generators is that the exciting current for the field of the direct-current generator is usually taken from its own rotor (since it is direct current) while the exciting current for the field of the alternating-current generator must always come from some outside source, usually a small direct-current generator. From this one may seeOne important difference between alternating- - Ответ на вопрос по английскому языку №19506One important difference between alternating- - Ответ на вопрос по английскому языку №19506
2024-02-022024-02-02СтудИзба
One important difference between alternating- - Ответ на вопрос по английскому языку №19506
Вопрос
One important difference between alternating- and direct-current generators is that the exciting current for the field of the direct-current generator is usually taken from its own rotor (since it is direct current) while the exciting current for the field of the alternating-current generator must always come from some outside source, usually a small direct-current generator. From this one may see that the direct-current generator is indispensable to the operation of the alternating-current generator.One might ask where the direct-current generator gets the current to supply the field coils in the beginning.
The answer to this in that there is usually what is called a little “residual magnetism” present in the filed poles. This furnishes a weak field upon which the generator “builds up”. If a field becomes completely demagnetized so that the generator will not build up, it is necessary to connect a battery or wires from another running generator to the terminals of the dead generator for an instant to furnish field excitation.
Keep in mind that the direct-current generator, like the alternating-current generator, is a device to convert mechanical power into electrical power, and that the direct-current motor like the alternating-current motor reverses this process. Just as the alternating-current generator may be used a synchronous motor without any changes being made, the direct-current generator will operate as a motor. The difference here is that any direct-current generator will operate as a motor (and visa versa), whereas the alternating-current generator will only operate as a synchronous motor. None of the other alternating-current motors will operate as generators.
Does the dc generator take exciting current for the field coils from outside source?
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false; not stated. true;
nastia1998l
