Q&A about FAQs about diesel generator sets

1. What are the conditions for paralleling two generator sets? What are the conditions for paralleling the machine?
Answer: The conditions for paralleling the machine are the same voltage, frequency and phase of the two generators at the moment. Generator sets are commonly known as 'three simultaneous'. It is generally recommended to use a parallel machine device to complete the parallel machine work. It is generally recommended to use a fully automatic parallel machine. Try not to manually parallel machine. Since the success or failure of manual parallel machine depends on human experience. The author boldly stated with more than 20 years of experience in power work, the reliable success rate of manual parallel machine of diesel generator is 0. The concept of manual convergence of the power supply system of the mains power system should never be used to apply a small power system, because the protection levels of the two are different.
2. What are the reasons for the high water temperature alarm and shutdown even if it is unable to use?
Answer: Water tank leaks or insufficient water volume; water temperature sensor is damaged; water tank water channel dirt is too thick or too much oil stain; fan belt is worn too much, and the pressure is insufficient; water pump is worn, and the pump water volume is insufficient; thermostat is not opened enough, and there is a phenomenon of jamming; cylinder gasket is damaged, and the water channel is connected to the cylinder; cylinder liner is too worn, and local water seepage is partially exposed; the ventilation in the computer room does not meet the requirements; engine is overloaded; (including engine fatigue) oil supply is too large.
3. Why must the generator (electric ball) work chamber be kept clean?
Answer: If the diesel engine absorbs dirty air, it will reduce the power; if the generator absorbs sand, dust and other impurities, it will damage the extreme edge between the static rotor gap, which will cause burning.
4. What level of energy does electric energy belong to? What are the characteristics of alternating current?
Answer: Electric energy belongs to secondary energy, alternating current is converted from mechanical energy, and direct current is converted from chemical energy. The characteristic of alternating current is that it cannot be stored and is now found for use.
5. Why does the diesel engine emit black smoke?
Answer: When the diesel engine is at high load, the exhaust gas emits black smoke easily. The natural process of black smoke is generally believed that when the diesel engine load is high, the fuel injected into the combustion chamber increases, and the temperature in the combustion chamber is higher. In addition, the diesel engine mixture forms unevenness, which will cause insufficient air to burn in local areas of the combustion chamber. The fuel decomposes under high temperature and lacks oxygen and polymerizes to form carbon smoke (carbon black). Carbon smoke is not pure carbon, but a polymer. The main component is carbon (more than 85%), but it also contains a small amount of oxygen, hydrogen and ash, and its composition changes with the load of the diesel engine. Collect the carbon smoke through a filter and put it under an electron microscope to observe. You can see that the diameter of large carbon smoke particles is 0.05mm Left and right. The high-temperature cracking reaction of combustion in diesel engines is inevitable, especially in diesel engines with space-mixed combustion. High-temperature gas surrounds liquid oil droplets, resulting in the most favorable condition for cracking reactions. High-speed photography of the combustion process confirmed that a large amount of black smoke will appear around the top dead center. However, under normal circumstances, carbon smoke can find air in the subsequent combustion and burn completely, so that the exhaust gas is free of black smoke. However, if the cylinder air is insufficient and the mixing process is slow, the negative cylinder temperature drops due to expansion, and carbon cannot be burned and polymerized into carbon smoke. The formation of carbon smoke will cause incomplete combustion, the diesel engine economy will decrease, the exhaust temperature will increase, black smoke will be emitted from the exhaust gas, and the surface area of ​​the combustion chamber will be carbon, and the load cannot progress. Carbon deposits will also cause piston rings or pistons to get stuck, valves will be bitten dead. Therefore, the diesel engine is not allowed to work under a long period of overload.
6. Why does there be water in the fuel tank and how to prevent it?
Answer: Qualified fuel will not contain impurities and moisture when leaving the factory, but will more or less mix dust, dirt and moisture during transportation and storage. When the fuel tank is not full, the moisture in the air in the box will easily form condensation water droplets and mix into the fuel. Pay attention to the following points when using and storing fuel: 1) The fuel must be stored in the fuel tank for more than 24 hours first to allow the water and impurities to settle before use; 2) After each work, try to fill the daily fuel tank as much as possible to prevent the moisture in the tank air from mixing into the fuel oil; 3) When filling oil, wipe the funnel and the end cap of the fuel tank first. When using a hand-crank pump, be careful not to extract the low-level sediment together; 4) Regularly open the fuel tank exhaust cock to remove accumulated water and precipitation.
7. What fault can cause the gear teeth of the motor (electric ball) group starter motor transmission gear?
Answer: The battery power is insufficient. The battery temperature is too high. The starter motor relay is not working. The starter motor transmission gear cannot mesh with the flywheel ring. The starter motor cannot rotate or cannot rotate. The starter motor does not rotate. The starter motor fails; the diesel engine cannot be separated from the starter motor after the diesel engine is running;
8. What is the main cause of AVR damage?
Answer: The AVR circuit consists of three parts: rectifying main circuit, voltage detection circuit, and comparison control circuit. Excluding the possibility of damage caused by the quality of the original electrical components, in the entire AVR circuit, the working frequency of the main circuit and the comparison control circuit change the most; among them, the rectifier bridge and transistors in the comparison circuit of the main circuit change more frequently, and the damage ratio accounts for more than 90% of the damage rate of the entire AVR; given that the AVR on the imported generator is a non-removal accessories, and it must be replaced if damaged, so we mainly analyze the causes of AVR damage on the generator, and avoiding AVR damage as much as possible is the most important thing. As long as it is used properly, the service life of AVR can be improved. The more stable the generator voltage, the smaller the frequency of variation in AVR; the smaller the switching action of the transistor in the comparison circuit, the smaller the probability of AVR damage; the relatively stable output load, the smaller the frequency of variation in AVR, the smaller the switching action of the transistor in the comparison circuit, the smaller the probability of AVR damage; the more stable the speed of the diesel engine, the smaller the impact of the oscillation of the changing current on AVR; the longer the difference between the three-phase load and the overload, the larger the difference between the three-phase load is the main reason for AVR damage; choose a generator set with E, F, and C fuel systems, because the frequency changes are small, the use of AVR will be more reliable.
9. What is the so-called reverse power transmission? What are the two serious consequences?
Answer: The situation where the self-produced generator (electric ball) sends power to the municipal network is called reverse power transmission. There are two serious consequences:
1) If the municipal network has not been powered off, the municipal network power supply and the self-produced generator power supply will be discontinued at different times, which will definitely destroy the unit. If the self-produced generator capacity is large, it will also cause the municipal network to fluctuate.
2) The municipal network has been powered out and is being inspected, and its own generator is back-sending power. This will cause some inspection staff to be electrocuted and die.
10. Why can’t the power shutdown or turn on the machine with load?
Answer: The power shutdown with load is an emergency shutdown, which has a large impact on the unit. The power boot with load is illegal operation and will cause damage to the power equipment used by the power generator.
11. What is the generator demagnetization and how should it be handled?
Answer: The generator is not used for a long time, resulting in the loss of residual magnetism contained in the iron core before leaving the factory, and the excitation coil cannot establish the proper magnetic field. At this time, the engine is running normally but cannot generate electricity. This phenomenon is new. There are many units that are not used for a long time. Treatment method:
1) If there is an excitation button, press the excitation button
2) If there is no excitation button, use a battery to charge it
3) With a load load, run for a few seconds for overspeed
12. What is the load order after power is turned on?
Answer: The load is carried from large to small
13. What is the order of unloading the load before the machine?
Answer: The load is unloaded from small to large and finally shut down.
14. What is the demagnetization of the generator (electric ball) and how should it be handled?
Answer: The generator (electric ball) is not used for a long time, resulting in the loss of the remaining magnet contained in the iron core before leaving the factory, and the excitation coil cannot establish the proper magnetic field. At this time, the engine is running normally but cannot generate electricity. There are many new machines or units that are not used for a long time. Treatment method:
1) If there is an excitation button, press the excitation button
2) If there is no excitation button, use a battery to charge it
3) With a light bulb load, run for overspeed for a few seconds.
15. What is the so-called three-phase and four-wire system?
Answer: There are 4 outgoing lines of the generator set, 3 of which are live wires and 1 is a neutral wire. The voltage between the live wire and the live wire is 380V. The voltage between the live wire and the live wire is 220V.
16. What is the case with a three-phase short circuit? What consequences will it have?
Answer: No load has passed between the live wires, and a direct short circuit is a three-phase short circuit. The consequences are very terrible, and in severe cases, it will lead to the destruction of the aircraft and death.