Diesel Generator Technicals
Diesel Generator Technicals – Herewith, the most common technical question and the answer for your Diesel Generator Sets. Let’s dig into it!
1. Conditions for generators parallelling? What devices for complete parallelling ?
Answer: Conditions for parallel use are instantaneous voltage, frequency, and phase of both machines. Commonly known as “three at a time”. Use special parallel devices to complete parallel work. It is generally recommended to use fully automatic cabinets. Try not to use manual parallel. Because manual parallel success or failure depends on the human experience. With more than 20 years of experience in electric power work, the author boldly states that the reliable success rate of a manual parallel diesel generator is equal to zero. Never use the manual parallel concept for a large electric power system to implement a small power supply system, as the levels of protection of the two are completely different.
2. What’s the power factor of 3-phase generator? Can power compensator be added to increase the power factor?
Answer: The power factor is 0.8. No, because charging and discharging the capacitor will cause small power supply fluctuations. And the unit oscillates.
3. Why do we require our customers to tighten all electrical contacts every 200 operating hours?
Answer: Diesel generator set is a vibrating working device. In addition, many domestically manufactured or assembled units have to use useless double nuts. The use of spring washers is useless. After the electric fasteners are loosened, a large contact resistance will be generated and the unit will not operate normally.
4. Why must the generator room be clean and free of quicksand on the ground?
Answer: If a diesel engine sucks in dirty air, the power will be reduced; if the generator sucks in the sand and other impurities, the insulation between the stator and rotor gaps will be damaged, and at worst will cause burnout.
5. Since 2002, why we don’t recommend neutral point grounding during installation?
Answer: 1) The new generation generator self-adjustment function is greatly improved; 2) In practice, it is found that the lightning failure rate of the neutral grounding unit is relatively high; 3) Grounding quality requirements are high, and ordinary users cannot do it. The unsafe working ground is not as good as grounding; 4) The neutral grounding unit will cover load leakage errors and grounding errors, and these faults and faults cannot be exposed in the condition of the high current power supply from the mains.
6. What should be considered when using neutral point units that are not earthed?
Answer: Line 0 may be filled because the capacitor voltage between the live line and the neutral point cannot be removed. The operator must think of line 0 as a charged body. This cannot be handled according to the utility’s power habits.
7. How to match UPS power and diesel generator to ensure stable UPS output?
Answer: 1) UPS is generally expressed in KVA apparent power, first multiply by 0.8 to convert it into KW units corresponding to the active power of the generator; 2) If a general generator is used, the UPS active power is multiplied by 2 to determine the Generator Power, that is, the generator power is twice the UPS power.
3) If a generator with PMG (permanent magnet engine excitation) is used, the UPS power is multiplied by 1.2 to determine the generator power, that is, the generator power is 1.2 times the UPS power.
8. Can electronic or electrical components marked with 500V withstand voltage to be used in the diesel generator control cabinet?
Answer: No. Because the 400 / 230V voltage stated on the diesel generator set is the effective voltage. The peak voltage is 1,414 times the effective stress. 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. Today, there are even several units of the same brand on the market, and some not. The user must know for himself when purchasing the unit. It is best to write in written material as a contract attachment. Generally, low-cost machines do not have a self-protection function.
10. How to identify counterfeit, inferior, and counterfeit domestic diesel engines?
Answer: First check if there is a factory certificate and a product certificate, this is an “identity certificate” for diesel engines leaving the factory and is required. Double-check the three main numbers on the certificate: 1) the nameplate number; 2) body number (generally on planes machined at the end of the flywheel, the font is convex); 3) oil pump nameplate number. Check these three numbers against the actual numbers on the diesel engine, and they must be accurate. If there is any doubt these three numbers can be reported to the manufacturer for verification.
11. After the operating electrician takes over the diesel generator, which three points should be verified first?
Answers: 1) Make sure the unit’s actual power is useful. Then determine the economic strength and reserve power. The method for approving the useful power of this unit is: the 12-hour rated power of the diesel engine is multiplied by 0.9 to get the data (kW). If the rated power of the generator is less than or equal to this data, the rated power of the generator is considered to be the actual useful power of the unit. If the rated power of the generator is greater than this data, the data should be used as the actual useful power of the unit; 2) Verify which type of personal protection function the unit has; 3) Verify that the unit’s power cord meets the requirements and that the protective grounding is reliable. Is phase load basically balanced?
12. There is a 22KW lift start motor, what size generator should be equipped?
Answer: 22 * 7 = 154KW (the elevator is a direct load starting model, and the instantaneous starting current is generally 7 times the rated current to ensure the elevator is moving at a constant speed). (That is, it must be equipped with a generator of at least 154KW)
13. How to calculate the optimal power (economic power) of the generator?
Answer: Best P = 3/4 * P (that is, 0.75 times rated power).
14. According to national regulations, how much higher engine power should a generic generator have than a generator power?
15. The engine power of some generators is expressed in horsepower. How do you convert the horsepower to international units of kilowatts?
Answer: 1 horsepower = 0.735 kilowatts, 1 kilowatt = 1.36 horsepower.
16. How to calculate the current of a three-phase generator?
Answer: I = P / (√3 Ucos φ), which is current = power (watts) / (√3 * 400 (volts) * 0.8)
The simplified 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 apparent power unit is KVA, which is used to express the capacity of transformers and UPS in our country; 2) The active power is 0.8 times the apparent power, and the unit is KW. Our country is ordinary power generation equipment and electrical equipment; 3) Diesel generator rated power refers to the power which can be operated continuously for 12 hours; 4) The maximum power is 1.1 times the rated power, but only 1 hour is allowed in 12 hours; 5) The economic power is 0.75 times the rated power, It is the output power that the diesel generator set can run for a long time indefinitely. When running at this power, the least fuel, and the lowest failure rate.
18. Why shouldn’t the diesel generator set operate for a long time when the power is less than 50% of the rated power?
Answer: Increased oil consumption makes diesel engines vulnerable to carbon build-up, which increases the failure rate and shortens the repair period.
19. The actual output power of the generator operation to the power meter or the ammeter shall prevail?
Answer: The current meter shall prevail; the power meter is for reference only.
20. A generator set of frequency, voltage is unstable its problem lies in the engine or generator?
Answer: In the engine.
21. A generator set of stable frequency, voltage instability of the problem lies in the engine or generator?
Answer: In the generator.
22. The generator is out of magnetism is how, how should be handled?
Answer: The generator is not used for a long time. It is resulting in the loss of remanent magnetism contained in the iron core before the factory. the excitation coil cannot establish a proper magnetic field, the engine runs normally but does not generate electricity, such phenomena new machine Or long-term unused units are more. Treatment: 1) the excitation button presses the excitation button, 2) no excitation button, with a battery to its magnetization, 3) with a light bulb load, overdrive for a few seconds.
23. The generator set after a period of time found that the rest of all normal but power down, what is the main reason?
Answer: a) the air filter is too dirty, not enough air intake which must be cleaned or replaced air filter; b) the fuel filter is too dirty, the injection volume is not enough, must be replaced or cleaned; c) the ignition time is not correct, must be adjusted.
24. There is a generator set with load after its voltage, frequency is stable, but the current is not stable, where the problem?
Answer: The problem is that the customer’s load is unstable, and the generator quality is absolutely no problem.
25. A generator set frequency is not stable, where is the main problem?
Answer: The main problem lies in the unstable speed of the generator.
26. Diesel generator sets in use is vital to pay attention to which point?
Answer: 1) water in the tank must be sufficient, and to maintain the work in the allowable temperature range; 2) lubricating oil must be in place, but not in excess, and to maintain the work in the allowable pressure range; 3) frequency stability at about 50HZ, voltage stability at about 400V; 4) three-phase current are within the rated range.
27. Diesel generator sets require frequent replacement or cleaning of which parts?
Answer: Diesel filter, oil filter, air filter. (Individual units and water filters)
28. What are the main advantages of brushless generators?
Answer: (1) free of carbon brush maintenance; (2) anti-radio interference; (3) reduce the loss of magnetic failure.
29. The insulation level of domestic generators is generally what?
Answer: domestic machine B class; Marathon brand machine and Leroy Summa brand machine and Stamford brand machine for H class.
30. What gasoline engine fuel needs to be mixed with gasoline and oil?
Answer: Two-stroke gasoline engine.
31. Diesel generator set basic equipment, including which six systems?
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 our customers to use our recommended engine oil in our sales work?
Answer: Oil is the blood of the engine. once the customer uses unqualified oil will lead to the engine tile bite, gear teeth, crankshaft deformation, and fracture, and other serious accidents until the whole machine are scrapped.
33. Why is it necessary to replace the oil and oil filter after using the new machine for a period of time?
Answer: Impurities will inevitably enter the oil sump during the break-in period of the new machine. Thus, the oil and oil filter will undergo physical or chemical quality changes.
34. Why do we ask customers to tilt the exhaust pipe downward 5-10 degrees when installing the unit?
Answer: To prevent the rain from entering the exhaust pipe and causing major accidents.
35. General diesel engines are equipped with manual fuel pumps and exhaust bolts, what are their functions?
Answer: Used to remove the air in the fuel pipe before starting.
36. Diesel generator set automation level how to divide?
Answer: Manual, self-start, self-start plus automatic utility conversion cabinet, remote three remote (remote control, telemetry, remote monitoring.)
37. Why the generator line voltage standard is 400V and not 380V?
Answer: Because there is a voltage drop loss in the line after the line.
38. Why require the use of diesel generating sets must be smooth air site?
Answer: The power of the diesel engine is directly affected by the number of inhaled air and air quality. the generator must have sufficient air to give cooling. Therefore, the use of the site must be air smooth.
39. Why in the installation of oil filters, diesel filters, oil, and water separators should not use tools to the above three devices rotate too tight, but only by hand to spin to not leak oil can?
Answer: Because if the seal is rotated too tightly by the oil bubble and the role of the body heating. There will be thermal expansion, resulting in large stress. Resulting in damage to the filter shell or separator shell itself. More serious is to cause damage to the body dowel mother so that it cannot be repaired.
40. What are the benefits of a customer who has purchased a self-starter, but not an automatic changeover cabinet as well?
Answer: 1) Once a power failure occurs in the city network, the unit will automatically start to speed up the manual power supply time; 2) If the front of the air switch connected to the lighting line can also ensure that the room lighting is not affected by power outages to facilitate the work of the operator.
41. The generator set to meet what conditions before closing the power supply?
Answer: water-cooled units, the water temperature of 56 degrees Celsius; air-cooled units, the body is slightly hot; no-load voltage and frequency are normal. Oil pressure is normal. Then the power can be turned on and fed.
42. What is the order of bringing load after starting power supply?
Answer: The load is brought in order from large to small.
43. What is the order of unloading before shutdown?
Answer: The load is unloaded in order from small to large and finally shut down
44. Why can’t shut down and start the machine with load?
Answer: Shutdown with load is an emergency stop and has a large impact on the unit. Start-up with load is a violation of the operation of power generation equipment and power equipment will bring damage.
45. The use of diesel generators in winter should pay attention to what?
Answer: 1) note that the tank should never freeze, prevent methods have to add a special long-lasting anti-rust, and antifreeze or the use of electric heating equipment to ensure that the room temperature above the freezing point; 2) is strictly prohibited open fire baking; 3) no-load preheating time to a little longer before the power.
46. The so-called three-phase four-wire system is what is going on?
Answer: The generator set has four wires, three of which are the firewire, one zero wire. The voltage between the fire line and the fire line is 380 V. Between the fire line and the zero lines is 220V.
47. Three-phase short circuit is how the matter? What are the consequences?
Answer: between the fire line without any load, a direct short circuit is a three-phase short circuit. The consequences are very terrible, serious will lead to machine destruction.
48. The so-called reverse power supply is what? What are the two serious consequences?
Answer: Self-provided generators to the city network is called a backward power supply. There are two serious consequences: a) the city network is not blacked out, the city network power supply and self-provided generator power generation non-simultaneous parallel will destroy the unit. If the self-generator capacity is larger, it will also make the city network shock; b) the city network has been blacked out for maintenance, the self-generator backward power supply. Then it will make the power supply department maintenance personnel electrocuted.
49. Why the commissioning staff must fully check whether all the fixed bolts of the unit are fixed intact before commissioning? Are all line interfaces intact?
Answer: After long-distance transportation, sometimes there are inevitably loose bolts and line interfaces, which may affect the commissioning and damage the machine.
50. What level of energy does electricity belong to? What are the characteristics of alternating current?
Answer: Electricity belongs to the second level of energy, alternating current is converted from mechanical energy, direct current is converted from chemical energy, the characteristics of alternating current are not stored, now found in use.
51. What does the common symbol GF of the domestic generator set mean?
Answer: represents twofold meaning: a) industrial frequency generator set that is suitable for our common power 50HZ generator set; b) domestic generator set.
52. The load carried by the generator in use must be kept in a three-phase balance?
Answer: Yes. The maximum deviation shall not exceed 25%, is strictly prohibited to run out of phase.
53. Four-stroke diesel engine refers to which four-strokes?
Answer: suction, compression, work, exhaust.
54. What is the biggest difference between diesel engines and gasoline engines?
Answer: 1) the cylinder pressure is different: diesel engine in the compression stage is the compression of air; gasoline engine in the compression stage is the compression of gasoline and air mixture; 2) ignition is different: diesel engine relies on atomized diesel sprayed to high-pressure gas spontaneous combustion; gasoline engine relies on spark plug ignition.
55. The power system “two tickets three systems” specifically refers to what?
Answer: Two tickets refer to the work ticket and operation ticket. That is any work and operation on the power equipment. Must first receive the work ticket and operation ticket issued by the person in charge of the shift. The parties involved must be executed according to the ticket; three systems refer to the handover system, tour inspection system, equipment switching system regularly.
That’s all! If you still have questions about your diesel generator, you are welcome to ask us. Leave a comment down below, or just directly message us!
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