Dynamic exciters are devices used in electrical engineering to provide the necessary excitation current to synchronous machines, such as generators and motors. They help maintain the magnetic field required for the operation of these machines, ensuring stable performance and efficiency. By adjusting the excitation current, dynamic exciters can control the output voltage and reactive power of the machine. These exciters typically consist of a rotating machine, often a small generator, that produces direct current (DC) to energize the main machine's rotor. Dynamic exciters are crucial in applications where precise control of voltage and power is needed, such as in power plants and large industrial systems involving synchronous generators and synchronous motors.