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.
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