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August 13, 2020
Why is your alternator old and broken? You know when you understand the alternator
The power source used by construction machinery has two kinds of battery and alternator. Construction machinery uses alternator as the main power source and storage battery as the auxiliary power source. During driving, the alternator provides power to the electrical equipment and charges the battery. The storage battery provides starting current when the construction machinery starts, and when the generator generates insufficient power, it can cooperate with the alternator to supply power.
Compared with DC generator, AC generator
It has the following characteristics:
1. Small size, light weight, high power;
2. When the engine is running at low speed, it can still be charged;
3. Fewer failures, long service life, simple warranty;
4. The structure of the equipped regulator is simple;
5. Low radio interference (rarely produce interference waves).
Understanding the structure of alternator
Alternator is mainly composed of rotor, stator, rectifier and end cover.
Composition of alternator
Structural decomposition of alternator
The structure of the alternator:
1) Rotor
Two pole claws: beak shape, generating AC electromotive force similar to sine wave.
Excitation winding or rotor winding: a current flows through it to generate a magnetic field; the lead wires are welded to two slip rings, which are insulated from the shaft. The generated magnetic flux magnetizes the claw poles into N pole and S pole respectively.
2) Stator
The stator is also called the armature. Its function is to generate three-phase AC electromotive force, which is composed of stator core and stator winding. There are two types of connection: delta connection and star connection. Mainly star connection, a few high-power generators adopt delta connection.
Stator composition:
Stator core: laminated by silicon steel sheets
Stator winding: the head ends are respectively connected with the diode of the rectifier, and the tail ends are connected together to form a neutral point (N).
Alternator type:
1. Six-tube alternator
2. Eight tube alternator
3. Nine-tube alternator
4. Eleven-tube alternator
Caterpillar, Caterpillar Excavator, Excavator Parts, Engine Parts, Caterpillar Parts
1. What is the purpose of the two diodes in the eight-tube alternator?
(1) Increase output power;
(2) To meet the requirements of increasing electrical equipment and increasing power consumption.
2.What is the purpose of the three diodes in the nine-tube alternator？
It is specially used to supply magnetic field current and control the charging indicator.
3. What is the purpose of the five diodes in the eleven-tube alternator?
Not only can it meet the requirements of output power, but also the charging indicator can be used to indicate the working condition to reach a perfect level.
4.Front and rear cover
Made of non-magnetic material aluminum alloy. Brushes and brush holders are installed in the back end cover.
Brush: made of copper powder and graphite powder, it is installed in the inner hole of the brush holder.
Brush holder: made of phenolic fiberglass plastic.
Features: less magnetic leakage, light weight, and good heat dissipation performance.
Power generation process
When the diesel engine starts, on the one hand, the lead-acid battery supplies a strong current to the starter through the starter switch. After the diesel engine runs, it uses the belt of the crankshaft pulley to drive the generator to rotate;
On the other hand, because the power switch is closed, the lead-acid battery supplies power to the electrical equipment, and at the same time, it also supplies the magnetic current to the field winding of the alternator through the regulator to achieve separate excitation.
