56 common problems with diesel generator sets

1. What are the conditions for the parallel use of two generator sets? What device is used to complete the parallel operation?
  Answer: The condition for parallel use is that the voltage, frequency and phase of the two machines are the same. Commonly known as "three simultaneous." Use a dedicated parallel device to complete the parallel operation. It is generally recommended to use fully automatic and cabinets. Try not to manually parallel. Because the success or failure of manual parallelism depends on human experience. The author has been vocal about more than 20 years of experience in electric power work. The reliable success rate of manual paralleling of diesel generators is equal to zero. It is never possible to apply a small power system with the concept of manual parallel power supply for the mains 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 improve the power factor?
  A: The power factor is 0.8. No, because the charging and discharging of the capacitor will cause fluctuations in the small power supply. And the unit oscillated.

3. Why do we ask the customer to carry out a fastening work for all electrical contact parts after every 200 hours of operation?
  Answer: Diesel generator sets are vibration workers. Moreover, many domestically produced or assembled units should be useless with double nuts. The use of the spring washer is useless. Once the electrical fastener is loose, a large contact resistance is generated, which causes the unit to operate abnormally.

4. Why should the generator room be clean and there is no floating sand on the ground?
  Answer: If the diesel engine inhales dirty air, the power will drop. If the generator inhales impurities such as sand, it will cause insulation damage between the stator and rotor gaps, which will cause burns.

5. Why has the company generally advised users to use neutral point grounding during installation since 2002?
  Answer: 1) The new generation of generator self-regulation function is greatly enhanced;
  2) In practice, it is found that the lightning failure rate of the neutral grounding unit is high.
  3) The grounding quality requirements are high and cannot be achieved by ordinary users. Unsafe working grounding is not as grounded as it is.
  4) Units with neutral grounding will cover the leakage faults and grounding errors of the load, and these faults and errors cannot be exposed under the condition of high-current power supply.

6. What should be paid attention to when using the ungrounded unit with neutral point?
  A: The 0 line may be charged because the capacitance voltage between the live line and the neutral point cannot be eliminated. The operator must regard the 0 line as a charged body. Can not be handled according to the utility of the city.

7. How can the UPS and diesel generators be matched in power to ensure stable UPS output?
  Answer: 1) UPS is generally expressed by the apparent power KVA, which is first converted into 0.8 by the unit KW which 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 generator power is twice the UPS power.
  3) If a generator with PMG (Permanent Magnet Excitation) is used, the power of the UPS is multiplied by 1.2 to determine the generator power, ie the generator power is 1.2 times the UPS power.

8. Can the electronic or electrical components with a withstand voltage of 500V be used for diesel generator control cabinets?
  A: No. Because the 400/230V voltage indicated 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 generator sets have self-protection?
  A: No. At present, there are some belts and some in the same brand of the same market. The user must figure it out when purchasing the unit. It is best to write in writing as an attachment to the contract. Generally, low-cost machines do not have self-protection function.

10. How to identify fake and fake domestic diesel engines?
  A: First check whether there is a factory certificate and product certificate. They are the “identity certificate” of the diesel engine factory. It is a must. Then check the three major numbers on the certificate. 1) Nameplate number; 2) Body number (the object is generally on the plane machined by the flywheel end, the font is convex); 3) The oil pump nameplate number. Checking these three major numbers against the actual number on the diesel engine must be accurate. If there are any doubts, the three major numbers can be reported to the manufacturer for verification.

11. After operating the electrician to take over the diesel generator set, which three points must be verified first?
  Answer: 1) Verify the actual useful power of the unit. Then determine the economic power, and the standby power. The method for verifying the true 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 the data, the rated power of the generator is determined as the true useful power of the unit. If the generator rated power is greater than this data, this data must be used as the actual useful power of the unit.
  2) Verify which types of self-protection functions the unit has.
  3) Verify that the power wiring of the unit is qualified, whether the protection grounding is reliable, and whether the three-phase load is basically balanced.

12. How many generator sets should be equipped with an elevator starter motor of 22 Kw?
  Answer: 22*7=154KW (the elevator is a direct load starter type, the instantaneous starting current is generally 7 times of the rated current, in order to ensure the uniform movement of the elevator). (ie at least 154KW generator set)

13. How is the optimal power (economic power) of the generator set calculated?
  Answer: P is optimal = 3/4*P rated (ie 0.75 times rated power).

14. Does the state stipulate that the engine power of a general generator set should be greater than the power of the generator? A: 10c/o.

15. Some generators' engine power is expressed in horsepower. How is the horsepower and international unit kilowatts converted?
  A: 1 horsepower = 0.735 Kw, 1 Kw = 1.36 hp.

16. How is the current of the three-phase generator calculated?
  Answer: I = P / (√3 Ucos φ )
  Ie current = power (Watts) / (√3 * 400 (volts) * 0.8).
  The formula is: I(A) = unit rated power (KW)* 1.8

17. What is the relationship between apparent power, active power, rated power, maximum power, and economic power?
  Answer: 1) The unit of apparent power is KVA. China is used to express the capacity of transformers and UPS.
  2) The active power is 0.8 times of the apparent power, and the unit is KW. China is used to power generation equipment and electrical equipment.
  3) The rated power of the 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 be operated for a long time without time limit. When this power is running, the fuel is the most economical and the failure rate is the lowest.

18. Why not allow diesel generator sets to operate for a long period of time at less than 50% of rated power.
  A: The oil consumption is increased, the diesel engine is prone to charcoal, the failure rate is increased, and the overhaul period is shortened.

19. Is the actual output power of the generator running based on the power meter or the current meter?
  A: The current meter is subject to accuracy. The power meter is for reference only.

20. The frequency and voltage of a generator set are unstable. Is the problem whether the engine or the generator?
  A: It is in the engine.

21, the frequency of a generator set is stable, the voltage is unstable. Is the problem whether the engine or the generator?
  A: It is the generator.

22, how is the generator lost magnetism, what should be done?
  Answer: The generator is not used for a long time, so that the residual magnets contained in the iron core are lost before leaving the factory. The excitation coil can not establish the proper magnetic field. At this time, the engine is running normally but the power is not generated. Or more units that are not used for a long time.
  Treatment method: 1) Press the excitation button with the excitation button, 2) Magnetize the battery with no excitation button, 3) Carry a bulb load and run for a few seconds.

23. After using the generator for a period of time, I found that everything else is normal but the power is decreasing. 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 unit is too dirty and the fuel injection quantity is insufficient. It must be replaced or cleaned.
  c. The ignition time is not correct and must be adjusted.

24. After a generator set has a load, its voltage and frequency are stable, but the current is unstable. What is the problem?
  A: The problem is that the customer's load is unstable, and the quality of the generator is absolutely no problem.

25. The frequency of a generator set is unstable. What are the main problems?
  A: The main problem is that the speed of the generator is unstable.

26. What are the important points that must be noted when using diesel generator sets?
  Answer: 1) The water in the tank must be sufficient and kept working within the allowable temperature range.
  2) Lubricating oil must be in place, but not excessive, and remain within the allowable pressure range.
  3) The frequency is stable at around 50HZ and the voltage is stable at around 400V.
  4) The three-phase currents are all within the rated range.

27. What are the parts that need to be replaced or cleaned frequently in diesel generator sets?
  A: Diesel filter, oil filter, air filter. (There are water filters for individual units)

28. What are the main advantages of brushless generators?
  Answer: (1) Eliminate the maintenance of carbon brushes;
  (2) Anti-radio interference;
  (3) Reduce the loss of magnetic failure.

29. What is the insulation rating of domestic generators?
  A: Domestic machine B grade; Marathon brand machine and Leroy Somer brand machine and Stanford brand machine are H class.

30. What fuels for gasoline engine engines require gasoline and oil blending?
  A: Two-stroke gasoline engine.

31. Which six systems are included in the basic equipment of diesel generator sets?
  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 advise customers to use the oil recommended by our company in sales?
  A: The oil is the blood of the engine. Once the customer uses the unqualified oil, the engine will cause serious accidents such as bearing bushing, gear teething, crankshaft deformation and breakage, and the whole machine will be scrapped.

33. Why do I need to change the oil and oil filter after using the new machine for a while?
  A: During the running-in period, it is inevitable that impurities will enter the oil sump during the running-in period, causing physical or chemical changes in the oil and oil filters.

34. Why do we require the customer to install the unit, the exhaust pipe should be tilted 5-10 degrees?
  A: In order to prevent rainwater from entering the exhaust pipe, a major accident will occur.

35. The general diesel engine is equipped with a manual oil pump and an exhaust bolt. What is its function? A: Use to remove air from the fuel pipe before starting.

36. How to classify the diesel generator set automation level?
  A: Manual, self-starting, self-starting plus automatic mains conversion cabinet, remote three remote (remote control, telemetry, remote monitoring.)

37. Why is the generator's outlet voltage standard 400V instead of 380V?
  A: Because the line after the line has voltage drop loss.

38. Why do you need to have a smooth air flow in the use of diesel generator sets?
  A: The output of the diesel engine is directly affected by the amount of air sucked in and the quality of the air. The generator must have sufficient air for cooling. Therefore, the use of the venue must be air fluent.

39. Why shouldn't the above three tools be screwed too tightly when installing the oil filter, diesel filter or oil-water separator, and just turn it by hand to not leak oil?
  Answer: Because if the screw is too tight, the sealing ring will expand and expand under the action of oil bubbles and the body temperature, which will cause great stress. Causes damage to the filter housing or the separator housing itself. What is more serious is that the body's aunt is damaged and cannot be repaired.

40. The customer has purchased the self-starting, but what are the benefits of not purchasing the automatic conversion cabinet?
  Answer: 1) Once the power grid is out of power, the unit will start automatically to speed up the manual power transmission time;
  2) If the lighting line is connected at the front end of the air switch, the lighting of the equipment room can be protected from the power outage, so that the operator can work;

41. What conditions can the generator set meet to send power?
  A: The water-cooled unit and the water temperature reach 56 degrees Celsius.
  Air-cooled unit, the body is slightly hot.
  The voltage frequency is normal at no load. The oil pressure is normal. It can be turned on and off.

42. What is the order of loading after power-on?
  A: The load is taken from big to small.

43. What is the order of unloading before shutting down?
  A: The load is removed from small to large, and finally shut down.

44. Why can't I turn off the load and turn it on?
  Answer: With the load shutdown is an emergency shutdown, which has a greater impact on the unit. Operation with a load is an illegal operation and will cause damage to the electrical equipment of the power generation equipment.

45. What should I pay attention to when using diesel generators in winter?