The result is that the field is concentrated inside the core, and almost no field lines leave the core.
Furthermore, if the coil is wrapped around a piece of iron, the current becomes even stronger. However, they represent a "modular" technology in that capacity can be added in small increments 5 - 20MW as needed, allowing utilities to reduce both capital expenditures and construction lead times.
This spinning shaft is connected to the rotor of a generator, and the generator produces electricity. Typical voltages for long distance transmission are in the range of 155,000 to 765,000 volts in order to reduce line losses. As they move, the magnets induce an electric current in the wire.
If we put a permanent magnet in this area of rotating field, or if we put in a coil whose current always runs in the same direction, then this becomes a synchronous motor.
So the back emf required is smaller, and the motor turns more slowly. That is the origin of the diagram shown here. When the motor is loaded, then the phase of the voltage becomes closer to that of the current it starts to look resistive and this apparent resistance gives a voltage. Or else continue here to find out about loudspeakers and transformers. Skip to main content.
In the following text, I shall largely use the 'torque on a magnet' picture, but be aware that the use of brushes or of AC current can cause the poles of the electromagnet in question to swap position when the current changes direction. As long as there is enough torque to overcome the load placed on the motor, internal friction etc. When inducing direct current, some mechanism must be employed to make sure the coils only cut through the magnetic field in one direction, or that the circuit only uses current from the coil cutting in that one direction.
This is illustrated below for a motor with wound stators above and permanent stators below. Instead of heat energy, they use kinetic energy, or the energy of motion. Position the two magnets, north to south, so that the magnetic field passes through the coil at right angles to the axles.
Since these new technologies are designed into plants from the start, they are less expensive to install. A typical regulator bank.
This is just a convention to make the orientation clear: Brushes introduce losses plus arcing and ozone production. These alternate energy technologies have been under development for several decades, and advocates believe the technical and political situation will now bring them into the market-place.
A self-excited motor produces its own field excitation. The animations were made by George Hatsidimitris.