The 56 Technical Questions and Answers of Diesel Generator Set– NO. 01-35

1. What are the conditions used by the two generator sets? What device to complete the parallel work?

Answer: The conditions used in parallel are the same voltage, frequency, and phase of the instantaneous voltage, frequency, and phase of the two machines. Commonly known as "three simultaneous". Use dedicated parallel installation to complete the parallel work. It is generally recommended to use fully automatic parallel cabinets. Try not to be manual. Because the success or failure of manual mergers depends on human experience. With more than 20 years of experience in power work, the author is bold to say that the reliable success rate of the manual parallel machinery of diesel generators is equal to 0. You must not use the concept of manual merger to apply a small power system with the concept of a large -scale power system, because the protection level of the two is completely different.

2. What is the power factor of the three -phase generator? Can we add power compensators to improve power factors?

Answer: The power factor is 0.8. No, because the charging and discharge of the capacitor can cause the fluctuation of small power supply. And the unit oscillation.

3. Why do we ask customers that after 200 hours of running the unit, we need to conduct a fastener work of all electrical contact parts?

Answer: The diesel generator set is a vibrator. And many domestic production or assemblies should be useless for double nuts. This is useless to use the spring cushion. Once the electrical fastener is relaxed, a large contact resistance will be generated, resulting in abnormal operation of the unit.

4. Why must the generator room be guaranteed and there is no floating sand on the ground?

Answer: If the diesel engine is inhaled in dirty air, the power will be reduced; if the generator inhales the impurities such as sand particles, the insulation between the fixed rotor gap will be destroyed, and the severe case will cause burning.

5. Why does our company generally not recommend that users use neutral point ground during installation since 2002?

Answer: 1) The self -adjustment function of the new generation of generators is greatly enhanced;

2) In practice, the lightning failure rate of the neutral point -to -ground unit is found.

3) The quality of grounding is high and the general users cannot do it. Unsafe work is worse than not ground.

4) The units with a neutral point ground will cover up the load leakage failure and ground errors, and these faults and errors cannot be exposed under large current power supply.

6. What are the issues should be paid attention to when using the neutral point?

Answer: The 0 line may be charged, because the capacitor voltage between the fire line and the neutral point cannot be eliminated. The operator must regard the 0 line as a charger. Can not be processed according to city electricity habits.

7. How can UPS and diesel generators be supported to ensure that UPS output is stable?

Answer: 1) UPS generally uses vision at the power KVA, first convert it to 0.8 to the unit KW with the same power as the generator.

2) If general generators are used, the effective power of the UPS is used to determine the power of the generator, that is, the power of the generator is twice the UPS power.

3) If the generator with a PMG (permanent magnet machine excitation) is used, the power of the generator is determined by 1.2 to determine the power of the generator, that is, the power of the generator is 1.2 times that of the UPS power.

8. Can the electronic or electrical elements that indicate 500V for 500V can be used for diesel generator control cabinets?

Answer: No. Because the 400/230V voltage marked on the diesel generator set is an 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. Are all diesel generator sets with self -protection functions?

Answer: No. At present, there are even some units in the market in the market. Users must figure out when buying a unit. It is best to write a written material as an attachment of the contract. Generally, low -cost machines do not have self -protection functions.

10. How to distinguish between fakes and inferiority and counterfeit domestic diesel engine?

Answer: First check whether there is a factor -in certificate and a product certificate. They are the "identity certificate" of the diesel engine factory, which must have. See the three major numbers on the book 1) Nameplate number; 2) the body number (the physical object is generally on the plane of the mechanical cutting and processing of the flywheel, the font is convex); 3) the oil pump nameplate number number. Check these three major numbers with the actual number on the diesel engine.

It must be accurate. If there are doubts, these three major numbers can be reported to the manufacturer.

11. After operating an electrician to take over the diesel generator crew, first of the three main points should be verified?

Answer: 1) Verify the real and useful power of the unit. Then determine economic power and spare power. The real useful power of the approved unit is: the 12 -hour rated power of the diesel engine is obtained by 0.9 to get a data (KW). If the rated power of the generator is less than or equal to the data, the rated power of the generator is determined as the real and useful power of the unit. If the rated power of the generator is greater than the data, the data must be used as the real and useful power of the unit.

2) Decover what kind of self -protection functions are available in the crew.

3) Verify whether the power wiring of the unit is qualified to protect whether the grounding is reliable, and whether the three -phase load is basically balanced. 12. There is a elevator starting motor of 22kW, how big should it be equipped with a generator set?

Answer: 22*7 = 154KW (The elevator is a direct load starting model, and the instantaneous start current is generally 7 times the rated current.

It can ensure that the elevator exercises a uniform speed). (That is, at least 154kW generator set)

13. How to calculate the best use power (economic power) of the generator set?

Answer: The best = 3/4*p lingers (that is, 0.75 times the rated power).

14. The state stipulates that the engine power of general generator sets should be greater than the power of the generator?

Answer: 10℅.

15. Some generator units of engine power uses horsepower, how can the horsepower and international units be converted?

Answer: 1 horsepower = 0.735 kW, 1 kilowatt = 1.36 horsepower.

16. How to calculate the current of the three -phase generator?

Answer: i = p / (√3 ucos φ)

That is, current = power (tile) / (√3 400 (伏) 0.8).

The simple formula is: i (a) = unit rated power (KW)* 1.8

17. The relationship between the relationship between power, power power, rated power, maximum power, and economic power?

Answer: 1) The unit of power is KVA, and my country is used to expressing the capacity of transformers and UPS.

2) The power is 0.8 times the power, and the unit is KW. my country is used to power generation equipment and electricity equipment.

3) The rated power of the diesel generator set refers to the power that can run continuously in 12 hours.

4) The maximum power is 1.1 times the rated power, but only 1 hour is allowed within 12 hours.

5) Economic power is 0.75 times the rated power, which is the output power that can operate long -term operation without time limit. When the power is running, the fuel is the most provincial and the lowest rate of failure.

18. Why not allow diesel generators to run for a long time when the rated power is lower than 50%.

Answer: Increased oil consumption, diesel engines are prone to charcoal, increase the failure rate, and shorten the overhaul cycle.

19. The actual output power of the generator is based on the power sheet or the current table is based on the current table?

Answer: The current table is based on the current, and the power table is only for reference.

20. The frequency and voltage of a generator set are unstable. The problem is the engine or generator?

Answer: The engine.

21. The frequency of a generator set is stable. The problem of unstable voltage is the engine or the generator?

Answer: lies in the generator.

22. What is the problem of being magnetic and how to deal with the generator?

Answer: The power generation is not used for a long time, which causes the removal of the removal of the removal of the iron core in the iron core before the factory is lost. The excitation coil cannot afford the proper magnetic field. Or there are many unused crew for a long time.

Processing method: 1) Press the excitation button with the excitation button, 2) If the magnetic buttons are unlimited, use the battery to fill it with it, 3) with a light bulb load, and run over a few seconds.

23. After a period of time, the generator crew found that everything was normal but the power decreased. What are the main reasons?

Answer: A. The air filter is too dirty and the air is not inhaled. At this time, it is necessary to clean or change the air filter. B. The fuel filtering device is too dirty and the amount of fuel injection is not enough. It must be replaced or cleaned.

C. The ignition time is not right and must be adjusted.

24. After there is a generator set with a load, its voltage and frequency are stable, but the current is unstable. Where is the problem?

Answer: The problem is that the customer's load is unstable, and the quality of the generator is definitely no problem.

25. The frequency of a generator set is unstable. Where is the main problem?

Answer: The main problem is that the speed of the generator is unstable.

26. What are the crucial points for the use of diesel generators?

Answer: 1) The water in the water tank must be sufficient and keep working within the allowable temperature range.

2) The lubricating oil must be in place, but it is not available and keeps working within the allowable pressure range.

3) The frequency is stable at about 50Hz, and the voltage is stable at about 400V.

4) Three -phase current is within the rated range.

27. What are the parts that need to be replaced or cleaned frequently?

Answer: diesel filter, oil filter, air filter. (Individual units and water filters)

28. What are the main advantages of a brush -free generator?

Answer: (1) Remove the maintenance of the carbon brush;

(2) Anti -radio interference;

(3) Reduced magnetic failure.

29. What is the insulation level of domestic generators?

Answer: Domestic machine B -level; marathon brand machine and Llelesenma brand machine and Stanfu brand machine H -level.

30. What gasoline engine engines are mixed with gasoline and oil?

Answer: Erdongstan gasoline engine.

31. Which of the six systems of the basic equipment of the diesel generator set?

Answer: (1) Oil lubrication system;

(2) fuel system;

(3) Control the protection system;

(4) Cooling and cooling system;

(5) exhaust system;

(6) Starting system;

32. Why do we try our best to use the oil recommended by our company in the sales work?

Answer: Oil is the blood of the engine. Once the customer uses unqualified oil, it will cause serious accidents such as the engine to kill, gear bearing, and crankshaft deformation breaks.

33. Why do new machines need to replace the oil and oil filter after a period of use?

Answer: The new machine is inevitable that impurities enter the oil bottom shell during the running -off period, causing the oil and oil filter to physical change or chemical change.

34. Why do we ask the customer to install the crew, should the smoke exhaust pipe tilt down 5-10 degrees?

Answer: In order to prevent rainwater from entering the smoke exhaust pipe, major accidents occur.

35. The general diesel engine is equipped with a manual oil pump and exhaust bolt. What is its role?

Answer: Used to exclude the air in the fuel pipe before mobilizing.

(Q&A NO. 35-56 can be found in the next article.)