# what is a rotating magnetic field?

would it be used in a d.c motor or a transformer or a alternator

Relevance

How about a little background information first? If you have 2 magnets, like charges would repel each other and opposite charges would attract each other. That is; N & N, S & S would repels each other. N & S would attract each other. This is a natural phenomenon.

Further more, if you wrap an iron core with an insulated winding and apply current (voltage) to it, this iron core would become an electro-magnet.

Now, consider 2 magnets are placed in a housing. One piece of magnet is fixed in place and the other piece is pivoted in the center so that it is free to rotate. When the like charges come together, the pivoted piece cannot move backwards. It has no choice but to rotate.

Now, consider if there are 2 iron-cored coils, called the field winding, you have one fixed in place, called the stator, and you have the other one pivoted in the center, called the armature. When you applying current to them separately, these 2 fields are electrically magnetized, as explained in the background information. If the current for the fileds are 180 degree out of phase, ie, the + always meet the + and the - always meet the -. The + always tries to chase the - and the - always tries chase the +. This phenomenon create a rotating motion. This is called the rotating magnetic field.

• ?
Lv 4
5 years ago

Rotating Magnetic Field

A rotating magnetic field is what happens in the stator of a 3 phase motor or generator.

If you imagine the generator as a magnet spinning within 3 coils placed 120 degrees apart. As the N of the magnet approaches a coil, it induces a voltage. So each coil will see a voltage as the Magnet passes. This voltage is then used to create a rotating magnetic field in the 3 coils of a motor to drive the shaft.

• Chuck
Lv 6

A rotating magnetic field is required in AC (induction) motors and alternators. In the case of an alternator, the field winding itself is usually on the rotating armature. When it is energized with direct current and the shaft rotated, it induces voltage in the stationary (stator) windings, and the shaft experiences mechanical resistance to being rotated if there is current flowing in the stator windings - its a motor in reverse.

For an AC induction motor, the three phases are 120 degrees out of phase with one another, which produces a rotating magnetic field around the axis of the motor (since the windings are spaced at 120 degrees with respect to each other). A single phase induction motor achieves a rotating magnetic field by having two windings, and one of them has a capacitor to alter the phase of the current in that winding.

• shaun
Lv 4
6 years ago

A rotating magnetic field is a magnetic field that has moving polarities in which its opposite poles rotate about a central point or axis. Ideally the rotation changes direction at a constant angular rate. This is a key principle in the operation of the alternating-current motor.

Rotating magnetic fields are often utilized for electromechanical applications such as induction motors and electric generators. However, they are also used in purely electrical applications such as induction regulators.

https://www.electrikals.com/

• Anonymous
5 years ago

The 3 phases of the motor are physically wound 120 degrees apart. Where the motor is powered, each phase produces a magnetic field. These are all added together vectorially. When you do this, you end up with one vector that rotates as the line voltages change.

• Anonymous