How does a generator with an excitation variable build up the voltage

The rotor has a rotor coil, which is connected with the external excitation device through the slip ring, when the machine is turned on, the generator is close to the rated speed, and the remanence of the generator is excited, and after the voltage is established, the generator voltage provides excitation current to the rotor through the excitation transformation and rectifier device.

If the remanence of the generator cannot be excited, the electricity of the battery (3-12V) is charged to the rotor, and after the voltage is established, the generator voltage is supplied to the rotor through the excitation transformer and rectifier device.

In terms of physical structure, the stator and rotor of the generator.

In addition to being a driving force, they are two parts that are completely independent and do not interfere with each other;

The stator of the generator is the active energy source, which generates an induced electromotive force.

The electric current, dragged by the prime mover, outputs alternating current outward.

The active power is determined by the motive force (oil, gas, air, water, etc.).

The rotor of the generator is reactive, and the windings bring in direct current from the outside.

The magnetic field is established, and the reactive power of the alternating current is transmitted to the outside under the drag of the prime mover, and the reactive power is determined by the direct current of the external input (mostly obtained by the spontaneous alternating current rectification of the generator).

size. From the electromagnetic principle, the rotor and the stator are closely linked, the active and reactive power of the generator are output by the stator, the torque of the rotor determines the size of the active power, and the DC current of the rotor coil determines the size of the reactive power.

In the case of open loop, it depends on the temporary power supply, and in the case of closed loop, it depends on the residual voltage or starting power supply.

In daily life, the lack of electricity has brought a lot of inconvenience to our production and life. It is a good solution to use standby power supply, and the generator set as a standby power source can choose a diesel generator or a gasoline generator. So, is it better to buy a generator set, is it a diesel generator, or a gasoline generator?

Difference Between Diesel Generator and Gasoline Generator.

1. The fuel is different, the diesel generator fuel is diesel, and the gasoline generator fuel is gasoline.

2. Different types of ignition, gasoline generators are ignited with spark plugs; Diesel generators are ignited with heat formed by compression.

3. The power range is different, and the power of the general gasoline generator is between; Diesel generator power range is 8-2000kw.

4. The cooling method is different, the gasoline generator is mainly air-cooled, with small volume and easy to move; Diesel generators are mainly water-cooled, which is large in size and inconvenient to move.

5. The use of different places, gasoline generators are generally used for household lighting and air conditioning electricity, diesel generators are mainly used for hotels, breeding enterprises, chemical enterprises, etc.

Knowing the difference between diesel generators and gasoline generators, let's take a look at whether diesel generators or gasoline generators are better?

Each is good in its own way. Gasoline generators have less power, but they are still small in size, and they are more convenient to move, and are mostly suitable for backup power supply in homes and small restaurants. Diesel generators are relatively heavy and large, and they may need to build a generator room, but they have a lot of power, a lot of electricity, and a lot of electrical equipment.

The basic principle of a generator is that a rotating magnetic field sweeps through the windings, creating an electromotive force in the windings that emits electricity. The rotating magnetic field is generated by the excitation current through the rotor, so the excitation is very important for the generator, for the general generator, without the excitation, it cannot send out electricity, whether the excitation is permanent magnet or electromagnetic.

Therefore, generator excitation has the following three main functions:

1. Maintain the generator terminal voltage at a given value, and when the generator load changes, the generator terminal voltage is constant by adjusting the strength of the magnetic field.

2. Reasonably distribute the reactive power between the parallel running units.

3. Improve the stability of the power system, including static stability, transient stability and dynamic stability.

The exciter mainly provides excitation current to the generator, and the rotating magnetic field sweeps through the windings, generating an electromotive force in the windings, thereby emitting electricity.

The function of the excitation transformer: to provide excitation power for the generator excitation device. Its capacity and secondary side voltage are calculated based on the strong excitation multiple, the generator fixed excitation voltage, and the rated excitation current.

It is expressed as follows: 1. Secondary voltage (line voltage) u2 = 2 * uf (. where p is the strong excitation angle, usually 5-15°.

2. Rated capacity s=. where ifn is the rated excitation current of the generator, which is the conversion coefficient of the full DC to AC.

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First of all, the principle of the generator is to cut the magnetic inductance line, and the exciter and excitation transformer are to enhance the magnetic field and make the power generation more powerful.

The exciter provides DC power for the magnetic field of the main motor, that is, it provides a controllable magnetic field strength for the main motor;

The excitation transformer is to remove the voltage from the stator of the main motor, and after conversion, it is used as an excitation power supply, with the same function but different ways.

The function is to provide excitation power for the generator excitation device. Specifically, it is manifested in:

1) Before the generator is not pressurized, the voltage at the end of the machine is 0, and the circuit breaker disconnects the generator stator coil from the primary coil of the step-up transformer, the generator coil does not have a closed loop, the excitation transformer is installed at the front end of the universal circuit breaker, after the turbine generator reaches a certain speed, close the demagnetization switch, the generator and the excitation transformer form a closed loop, press the excitation button, and the generator uses the remanent magnet to build up the voltage immediately (200V 300V), Increasing the speed of the steam turbine and adjusting the excitation voltage can make the output of the generator meet the requirements of grid connection.

2) After the output of the excitation transformer passes through rectification, it forms an excitation power supply for the thyristor regulating generator.

The excitation transformer is a device that provides three-phase AC excitation power supply for the generator excitation system, and the excitation system converts the three-phase power supply into the DC power supply of the generator rotor through the thyristor, forming the generator excitation magnetic field, and adjusting the thyristor trigger angle through the excitation system to achieve the purpose of adjusting the motor terminal voltage and reactive power. It is usually connected to the generator outlet end, because the generator outlet voltage is high, and the rated voltage of the excitation system is low, so a step-down transformer is required.

The function of the excitation transformer is to install a voltage transformer from the outlet of the generator to achieve sampling adjustment and provide excitation power supply to the excitation device. Specifically**I don't know what to do or ask about.

The high voltage at the machine end is converted into a low voltage, and the rotor current is supplied to the generator after rectification.

Provide the excitation current required by the generator. It is a self-consubstantial excitation magnet.

The AC power supply of the exciter is taken from this generator, and the generator cannot be built with pressure, so how can the input excitation current and voltage be normal?

For the AC power supply that is connected to the other connection, the input excitation current and voltage are normal, but the voltage cannot be built, and the power generation coil (including the external connector wire) is at least one phase broken. Or the speed of the power engine is simply not enough.

The exciter is connected to the AC power supply, the DC output is terminated with a 220V, 300-2000W electric furnace, the output DC waveform is measured with an oscilloscope, the excitation button is increased or decreased, and the waveform is normal, then check 1, generator DC system, wiring, carbon brush, coil. 2. Generator AC system, wiring, coils. 3. Power machine.

If the waveform is abnormal, check the exciter.

There are multiple diodes in the exciter, and there are generally three thyristors.

Hello! The excitation generator is generally an alternator with a rectifier diode.

But what you said "the input excitation current and voltage is normal", then it basically proves that the diode is not broken?

Which line is the "current voltage"?

This is not necessarily, it depends on the excitation mode of the generator and the outgoing specifications of the generator. For example, in addition to the square winding, the generator also has a secondary winding --- for excitation, then there is no need for an excitation transformer; Another example is brushless excitation, at this time, the excitation power required is very small, and a small power transformer may be required, or a transformer may not be used, but the voltage regulation is directly regulated by thyristor. If this condition is a little more sufficient, the answer can be clearer.

Generally, the outlet voltage is high, and the outlet voltage is low.

The excitation classification of generators is first divided into self-excitation and other excitation. For small generators, self-excitation or harmonic excitation is generally used. Large-scale generators generally use separate excitation.

Phase compound excitation and harmonic excitation are similar in structure, both of which use the excitation current to "draw" from the armature winding, but the way of absorption has changed.

Generally speaking, the forced excitation belongs to a kind of other excitation. That is, the excitation current does not come from the armature winding, but from somewhere else. For large-scale generators, the excitation system is generally specially equipped with an excitation generator or other excitation systems; The brushless excitation generator is installed on the same blocked shaft of the main generator to save the space of the generator.