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Welcome to the website of Guangzhou Songge Electromechanical Equipment Co., Ltd.

松格机电

Professional generator set manufacturer sales lease maintenance

minshencao@hotmail.com Songge Electromechanical Consulting Hotline 020-84851836 minshencao@hotmail.com

Contact Songge Mechanical

Contact Songge Mechanical

Cummins generator set-Yuchai generator set-Silent diesel generator-Guangzhou Songge Mechanical and Electrical Co., Ltd.

020-84851836 Consulting Hotline: 020-84851836

曹先生 Contact: Mr. Cao

13609022338 Mobile: 13609022338

020-34865288 Fax: 020-34865288

342958639@qq.com Email: 342958639@qq.com

广东省广州市沙湾镇大涌口第二工业区1号 Address: No. 1 Second Industrial Zone, Dayongkou, Shawan Town, Guangzhou City, Guangdong Province

56 technical questions and answers about diesel generator sets

1. What are the conditions for using two generators in parallel? What device is used to complete the parallel work?
Answer: The conditions for parallel use are that the instantaneous voltage, frequency and phase of the two machines are the same. Commonly known as "three simultaneous". Use a special parallel device to complete the parallel work. It is generally recommended to use a fully automatic cabinet. Try not to use manual parallel. Because the success or failure of manual parallelism depends on human experience. With more than 20 years of experience in electrical work, the author ventures to say that the reliable success rate of manual parallel operation of diesel generators is equal to zero. Never use the concept of manual parallel operation of a large power system for a commercial power system to apply a small power system, because the protection levels of the two are completely different.
2. What is the power factor of the three-phase generator? Can I add a power compensator to increase the power factor?
Answer: The power factor is 0.8. No, because the charging and discharging of capacitors will cause small power supply fluctuations. And the unit oscillates.
3. Why do we require customers to perform a tightening of all electrical contacts after every 200 hours of operation?
Answer: Diesel generators are vibration workers. And many domestically produced or assembled units should be useless with double nuts. The use of this spring washer is not good. Once the electrical fastener is loosened, it will produce a large contact resistance, which will cause the unit to operate abnormally.
4. Why must the generator room be clean and free of floating sand?
Answer: If the diesel engine sucks dirty air, it will reduce its power; if the generator sucks sand and other impurities, the insulation between the stator and rotor gap will be damaged, and in severe cases, it will burn.
5. Why does our company generally not recommend that users use neutral grounding during installation since 2002?
Answer: 1) The self-regulation function of the new generation generator is greatly enhanced;
2) In practice, it is found that the lightning failure rate of neutral-grounded units is high.
3) The grounding quality is high and cannot be achieved by general users. It is better to be ungrounded for unsafe work.
4) The unit grounded at the neutral point will cover the leakage fault and ground fault of the load, and these faults and faults cannot be exposed under the condition of high-current power supply from the city power supply.
6. What problems should be paid attention to when the unit is not grounded at the neutral point?
Answer: Line 0 may be live because the capacitor voltage between the live line and the neutral point cannot be eliminated. The operator must view the 0 line as a charged body. Cannot be handled according to the mains habit.
7. How can the UPS and diesel generators be matched to ensure the UPS output stability?
Answer: 1) UPS is generally expressed by the apparent power KVA. First, multiply it by 0.8 to convert it into the unit KW that is consistent with the active power of the generator.
2) If a general generator is used, multiply the active power of the UPS by 2 to determine the power of the generator, that is, the power of the generator is twice the power of the UPS.
3) If a generator with PMG (Permanent Magnet Excitation) is used, multiply the power of the UPS by 1.2 to determine the power of the generator, that is, the power of the generator is 1.2 times the power of the UPS.
8. Can electronic or electrical components marked with a withstand voltage of 500V be used in a diesel generator control cabinet?
Answer: No. Because the 400 / 230V voltage marked on the diesel generator set is the effective voltage. Its peak voltage is 1.414 times the effective voltage. That is, the peak voltage of the diesel generator is Umax = 566 / 325V.
9. Do all diesel generators have a self-protection function?
Answer: No. Currently on the market, there are some with or without the same brand of units. The user must figure it out when purchasing the unit. It would be better to write in writing as an attachment to the contract. Generally low-priced machines do not have self-protection.
10. How to identify fake and inferior domestic diesel engines?
Answer: First check whether there is a certificate of delivery and a product certificate. They are the "identity certificate" of the diesel engine and must be available. Re-check the three major numbers on the certificate 1) Nameplate number; 2) Body number (generally on the plane machined on the flywheel end, the font is convex); 3) Oil pump nameplate number. The three numbers must be checked against the actual numbers on the diesel engine. If there are any doubts, the three major numbers can be reported to the manufacturer for verification.
11. After the electrician took over the diesel generator set, which three points should be checked first?
Answer: 1) Verify the real useful power of the unit. Then determine the economic power, and reserve power. The method for verifying the real useful power of the unit is: a 12-hour rated power of the diesel engine multiplied by 0.9 to obtain a data (kw). If the rated power of the generator is less than or equal to this data, the rated real power of the unit is determined as the real useful power of the unit. If the rated power of the generator is greater than this data, the data must be used as the real useful power of the unit.
2) Verify which self-protection functions the unit has.
3) Check whether the power connection of the unit is qualified, whether the protective grounding is reliable, and whether the three-phase load is basically balanced.
12. There is an elevator starting motor of 22KW. How big a generator set should be equipped?
Answer: 22 * 7 = 154KW (the elevator is a direct starting model with load, and the instantaneous starting current is generally 7 times the rated current to ensure that the elevator can move at a uniform speed) (Ie at least 154KW generator set)
13. How to calculate the optimal power (economic power) of the generator set?
Answer: P best = 3/4 * P rating (that is, 0.75 times the rated power).
14. The state stipulates that the engine power of a general generator set should be greater than the generator power? Answer: 10 cents.
15. The engine power of some generator sets is expressed by horsepower. How to convert the horsepower to the international unit kilowatt?
Answer: 1 hp = 0.735 kW, 1 kW = 1.36 hp.
16. How to calculate the current of a three-phase generator?
Answer: I = P / (√3 Ucos φ)
That is, current = power (W) / (√3 * 400 (V) * 0.8).
The short-cut formula is: I (A) = Unit rated power (KW) * 1.8
17. The relationship between apparent power, active power, rated power, maximum power, and economic power?
Answer: 1) The unit of apparent power is KVA. Our country is used to express the capacity of transformers and UPS.
2) The active power is 0.8 times the apparent power, and the unit is KW. China is used to generate electricity and equipment.
3) The rated power of a diesel generator set refers to the power that can be continuously operated for 12 hours.
4) The maximum power is 1.1 times the rated power, but only 1 hour is allowed within 12 hours.
5) The economic power is 0.75 times of the rated power, which is the output power of the diesel generator set that can run for a long time without being limited by time. When running at this power, the fuel is the most economical and the failure rate is the lowest.
18. Why is the diesel generator set not allowed to run for a long time under the condition of less than 50% of the rated power?
Answer: Increased oil consumption, easy carbon build-up of diesel engines, increased failure rates, and shortened overhaul cycles.
19. Is the actual output power of the generator based on the power meter or the ammeter?
Answer: The ammeter is prevailing. The power meter is for reference only.
20. The frequency and voltage of a generator set are unstable. The problem lies with the engine or generator?
Answer: It's the engine.
21. The frequency of a generator set is stable and the voltage is unstable. The problem lies with the engine or generator?
Answer: It is the generator.
22. What is the problem of generator demagnetization and what should I do?
Answer: The generator is not used for a long time, which causes the residual magnetism contained in the iron core to be lost before leaving the factory. The excitation coil cannot establish the proper magnetic field. At this time, the engine is running normally but no power is generated. Or long-term unused units.
Treatment method: 1) press the excitation button with the excitation button, 2) magnetize it with the battery without the excitation button, 3) carry a light bulb load and run at high speed for several seconds.
23. After using the generator for a period of time, it is found that everything else is normal but the power is reduced. What is the main reason?
Answer: a. The air filter is too dirty and the intake air is not enough. At this time, the air filter must be cleaned or replaced.
b. The fuel filter is too dirty, and the fuel injection volume is not enough. It must be replaced or cleaned.
c. The ignition time is not correct and must be adjusted.
24. There is a generator with a stable voltage and frequency, but the current is unstable. What's the problem?
Answer: The problem is that the customer's load is unstable, and the quality of the generator is absolutely no problem.
25. What is the main problem of the unstable frequency of a generator set?
Answer: The main problem is the unstable speed of the generator.
26. What are the important points that diesel generators must pay attention to in use?
Answer: 1) The water in the water tank must be sufficient and keep working within the allowed temperature range.
2) The lubricating oil must be in place, but not excessive, and keep working within the allowable pressure range.
3) The frequency is stable around 50HZ and the voltage is stable around 400V.
4) The three-phase currents are all within the rated range.
27. What are the parts that diesel generator sets need to be replaced or cleaned frequently?
Answer: Diesel filter, oil filter, air filter. (Some units also have water filters)
28. What are the main advantages of brushless generators?
Answer: (1) Eliminate the maintenance of carbon brushes;
(2) Anti-radio interference;
(3) Reduce loss of magnetic field failure.
29. What is the insulation level of domestic generators?
Answer: Domestic machine B grade; Marathon brand machine, Lilaisenma brand machine and Stanford brand machine are H grade.
30. What kind of gasoline engine fuel requires gasoline and oil blending?
Answer: Two-stroke gasoline engine.
31. Which six systems does the basic equipment of diesel generator set include?
Answer: (1) Oil lubrication system;
(2) Fuel system;
(3) Control and protection system;
(4) Cooling and cooling system;
(5) Exhaust system;
(6) Starting system;
32. Why do we try our best to recommend customers to use the oil recommended by our company in the sales work?
A: Engine oil is the blood of the engine. Once the customer uses unqualified engine oil, it will lead to serious accidents such as engine bite, gear cracking, crankshaft deformation and fracture, etc., until the whole machine is scrapped.
33. Why do I need to change the oil and oil filter after using the new machine for a period of time?
Answer: During the running-in period of the new machine, impurities will inevitably enter the oil pan, which will cause physical or chemical changes in the oil and oil filters.
34. Why do we require customers to incline the smoke exhaust pipe 5-10 degrees when installing the unit?
Answer: To prevent rainwater from entering the exhaust pipe, leading to a major accident.
35. General diesel engines are equipped with manual oil pumps and exhaust bolts. What is the role of them? Answer: Used to remove air from the fuel pipe before starting.
36, how to divide the diesel generator set automation level?
Answer: Manual, self-starting, self-starting and automatic mains conversion cabinet, long distance three remote (remote control, telemetry, remote monitoring.)
37. Why is the output voltage standard of the generator 400V instead of 380V?
Answer: Because there is voltage drop loss on the line after outgoing.
38. Why is the use of diesel generators required to have smooth air?
Answer: The output of a diesel engine is directly affected by the amount of air sucked in and the air quality. The generator must also have sufficient air to cool it. So the use site must be smooth.
39. Why shouldn't tools be used to tighten the above three devices too tightly when installing the oil filter, diesel filter, oil-water separator, and only by hand to prevent oil leakage?
Answer: Because if it is tightened too tightly, its sealing ring will thermally expand under the action of oil bubbles and the temperature of the body, resulting in great stress. Causes damage to the filter housing or the separator housing itself. What's more serious is the damage to the body's mother-in-law that makes it impossible to repair.
40. If the customer purchased the self-starter, but what is the benefit of not purchasing the automatic conversion cabinet?
Answer: 1) Once a power outage occurs in the city network, the unit will automatically start to speed up the manual power transmission time;
2) If the lighting cable is connected to the front of the air switch, the lighting of the equipment room can also be protected from power outages to facilitate the work of operators;
41. What conditions can a generator set meet before it can be closed for transmission?
Answer: For water-cooled units, the water temperature reaches 56 degrees Celsius.
Air-cooled units and airframes are slightly hot.
The voltage frequency is normal at no load. The oil pressure is normal. Before closing the power transmission.
42. What is the load sequence after power on?
Answer: The load is carried in order from large to small.
43. What is the load unloading sequence before shutdown?
Answer: The load is unloaded in order from small to large, and finally shut down.
44. Why can't I turn off and on with load?
Answer: Shut down with load is an emergency shutdown, which has a great impact on the unit. Starting with load is an illegal operation and will cause damage to the power generation equipment.
45. What should I pay attention to when using diesel generators in winter?
Answer: 1) Pay attention to the fact that the water tank must not be frozen. Preventive methods include adding special long-term antirust, antifreeze or using electric heating equipment to ensure that the room temperature is above the freezing point.
2) Open baking is strictly prohibited.
3) The no-load warm-up time should be a little longer before power transmission.
46. What is the so-called three-phase four-wire system?
Answer: There are 4 outgoing lines of the generator set, of which 3 are live wires and 1 is the neutral wire. The voltage between live wire and live wire is 380V. 220V between live and neutral.
47. What's wrong with three-phase short circuit? What are the consequences?
Answer: A direct short circuit is a three-phase short circuit without any load between the live wires. The consequences are terrible, and serious can cause machine death.
48. What is the so-called reverse transmission? What are the two serious consequences?
Answer: The situation where the self-provided generator sends power to the city network is called reverse power transmission. There are two serious consequences:
a) There is no power outage in the city grid. Asynchronous parallel connection between its city grid power source and its own generator power source will destroy the unit. If the self-provided generator has a large capacity, it will also cause the network to oscillate.
b) The city grid is out of power and under maintenance, and its own generator is transmitting power back. Will cause the electric power department maintenance personnel to be killed by electric shock.
49. Why does the commissioning staff have to check all the fixing bolts of the unit completely before commissioning? Are all line interfaces intact?
Answer: After the unit is transported for a long distance, sometimes it is unavoidable that the bolts and line interfaces are loose or dropped. The lighter affects the debugging and the machine is damaged.
50. What level of energy does electric energy belong to? What are the characteristics of alternating current?
Answer: Electrical energy is a secondary energy source. AC power is converted from mechanical energy and DC power is converted from chemical energy. The characteristic of AC power is that it cannot be stored.
51. What does the general symbol GF of domestic generator set mean?
Answer: It stands for double meaning:
a) Power frequency generator set is suitable for China's universal power 50HZ generator set.
b) Domestic generators.
52. Does the load on the generator have to maintain three-phase balance during use?
Answer: Yes. The maximum deviation must not exceed 25%. Phase loss operation is strictly prohibited.
53. Which four strokes does a four-stroke diesel engine refer to?
Answer: Inhale, compress, do work, exhaust.
54. What is the biggest difference between a diesel engine and a gasoline engine?
Answer: 1) The pressure in the cylinder is different.
Diesel engines compress air during the compression stroke phase;
Gasoline engines compress gasoline and air mixtures during the compression stroke phase.
2) Different ignition methods.
Diesel engines rely on atomized diesel to spontaneously ignite high-pressure gas;
Gasoline engines rely on spark plugs to ignite.
55. What does the "two-vote, three-system" system of power systems specifically mean?
Answer: Two tickets refer to work tickets and operation tickets. That is, any work and operations performed on electrical equipment. Must first receive the work and operation tickets issued by the person in charge of the shift. The parties must execute by ticket.
The three systems refer to the handover system, roving inspection system, and regular equipment switching system.
56. When, where and who was the inventor of the world's first practical diesel engine? What is the current situation?
Answer: The first diesel engine in the world was born in Augsburg, Germany in 1897, and was invented by Rudolf Diesel, the founder of MAN. Currently the English name of the diesel engine is the name of the founder Diesel.
MAN is the most professional diesel engine manufacturing company in the world today, with a single unit capacity of up to 15000KW. Is the main power supplier for the marine shipping industry. Large diesel power plants in China also rely on MAN companies, such as Guangdong Huizhou Dongjiang Power Plant (100,000 KW). Foshan Power Plant (80,000 KW) are all units provided by MAN.
Currently, the world's earliest diesel engine is stored in the exhibition hall of the German National Museum.