Difference Between DC Generator and Synchronous Generator

A DC generator is a device that converts mechanical energy into DC power. It is mainly used as a DC motor for DC motor, electrolysis, electroplating, electric smelting, charging and excitation of an alternator.

The working principle of the DC generator is to change the alternating electromotive force generated in the armature coil by the commutation function of the commutator and the brush, so that it changes from the brush end to the DC electromotive force because the brush A passes through the commutation. The electromotive force drawn by the sheet is always the electromotive force in the side of the coil that cuts the N-pole magnetic field lines. Therefore, the brush A always has a positive polarity, and the same reason, the brush B always has a negative polarity.

Synchronous generator, that is, an alternator with the same rotor speed as the rotating magnetic field of the stator. According to the structure, it can be divided into two types: a rotating armature and a rotating magnetic field.

Synchronous generators are one of the most commonly used alternators. In the modern power industry, it is widely used in hydropower, thermal power, nuclear power generation and diesel power generation.A synchronous motor that operates as a generator is one of the most commonly used alternators. In the modern power industry, it is widely used in hydropower, thermal power, nuclear power generation and diesel engine.

Electricity. Since the synchronous generator generally adopts DC excitation, when the single machine operates independently, the voltage of the generator can be conveniently adjusted by adjusting the excitation current. If it is integrated into the grid operation, the voltage is determined by the grid and cannot be changed. At this time, the result of adjusting the excitation current is to adjust the power factor and reactive power of the motor.

Classification of Synchronous Generator

Rotating magnetic pole

(Most synchronous generators): The pole is on the rotor and the armature winding is on the stator. The rotor is further divided into:

Hidden pole: high speed motor (steam turbine), distributed winding;

Salient pole: low speed motor (hydroturbine), concentrated winding.

Rotating armature

(small capacity or special purpose, such as synchronous motor AC exciter): the magnetic pole is on the stator and the armature winding is on the rotor.

The voltage change rate of the synchronous generator is about 20 to 40%. Both industrial and household loads require a constant voltage. For this reason, as the load current increases, the excitation current must be adjusted accordingly.

Structure

The structure of synchronous generator is divided into high speed and low (medium) speed according to its speed.

The former is mostly used in thermal power plants and nuclear power plants; the latter is mostly linked to low-speed turbines or diesel engines. In structure, high-speed synchronous generator uses hidden pole rotor, and low (medium) speed synchronous generator uses salient pole rotor.