## 56 technical questions and answers of diesel generator set–no. 20

16. How to calculate the current of a three-phase generator?
Answer: I = P / (√3 Ucos φ) that is, current = power (watts) / (√3 *400(volt) * 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 unit of apparent power 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, in KW, which is used in power generation equipment and electrical equipment in my country.
3) The rated power of a diesel generator set refers to the power that can be operated continuously 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 the rated power, which is the output power that the diesel generator set can run for a long time without time limitation. When running at this power, the fuel is the least and the failure rate is the lowest.
18. Why is it not allowed for diesel generator sets to run for a long time when the power is less than 50% of the rated power.
Answer: Increased oil consumption makes diesel engines prone to carbon formation, which increases the failure rate and shortens the overhaul period.
19. The actual output power of the generator during operation is based on the wattmeter or the ammeter?
Answer: The ammeter shall prevail, and the power meter is for reference only.
20. The frequency and voltage of a generator set are both unstable. Is the problem with the engine or the generator?
Answer: It lies in the engine.

Post time: May-17-2021

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