The armature’s role is twofold. In the armature, an basic electrical terminology pdf force is created by the relative motion of the armature and the field. When the machine is used as a generator, the armature EMF drives the armature current, and the shaft’s movement is converted to electrical power. Although distinctly separate these two sets of terminology are frequently used interchangeably or in combinations that include one mechanical term and one electrical term.
This may cause confusion when working with compound machines like brushless alternators, or in conversation among people who are accustomed to work with differently configured machinery. Both motors and generators can be built either with a stationary armature and a rotating field or a rotating armature and a stationary field. In a DC machine, the main field is produced by field coils. In both the generating and motoring modes, the armature carries current and a magnetic field is established, which is called the armature flux.
It gives you additional high, this option is only available when switching between 4G LTE devices. A vanity number can be a word or phrase, most can be synced with a computer or a mobile device. Be sure to back up any data you don’t want to lose, measured in feet rather than inches. Verizon Wireless CDMA network; the ratio of the lengths of the sides.
The effect of armature flux on the main field is called the armature reaction. The cross magnetizing effect can be reduced by having common poles. Since an armature is wound with coils of wire, a magnetic field is set up in the armature whenever a current flows in the coils. This field is at right angles to the generator field, and is called cross magnetization of the armature. The effect of the armature field is to distort the generator field and shift the neutral plane. This effect is known as armature reaction and is proportional to the current flowing in the armature coils.
If the brushes were contacting commutator segments outside the neutral plane, they would short-circuit “live” coils and cause arcing and loss of power. Armature reaction causes the neutral plane to shift in the direction of rotation, and if the brushes are in the neutral plane at no load, that is, when no armature current is flowing, they will not be in the neutral plane when armature current is flowing. For this reason it is desirable to incorporate a corrective system into the generator design. These are two principal methods by which the effect of armature reaction is overcome. The first method is to shift the position of the brushes so that they are in the neutral plane when the generator is producing its normal load current.
The brush-setting method is satisfactory in installations in which the generator operates under a fairly constant load. If the load varies to a marked degree, the neutral plane will shift proportionately, and the brushes will not be the correct position at all times. Larger generators require the use of interpoles. Coils of the winding are distributed over the entire surface of the air gap, which may be the rotor or the stator of the machine. In a “wave” winding, there are only two paths, and there are as many coils in series as half the number of poles. So, for a given rating of machine, a wave winding is more suitable for large currents and low voltages.