☆1．Overview of diesel generators
☆1.1 Diesel generator description
Weifang Junwei Machinery Co., Ltd diesel generators have the main brands as follows: Ricardo、Weichai、Yuchai、Cummins, and so on. If customers have special requirements, we can also configure other brands.
☆1.1.1 Generator type designation：
* For example: ZBF800PTFG1 means.6-6.6kV Voltage level, the alternating current frequency is 50Hz, the common power is 800kW, German Benz engine with Leroy-Somer alternator trailer-type anti-rain mobile power station.
⑴ Engine Code ——————————————————————————- It consists of 1 to 2 letters
⑵ Alternator Code ————————————————————————— It consists of 1 to 2 letters
⑶ Generator Power ————————— Power values are composed of Arabic numerals, not unit symbols
⑷ Generator Status —————————————————- P—Prime Generator S—Standby Generator
⑸ Type of power station（The general generator is omitted here）
⑹ Function Code （Ordinary generator and marine generator are omitted here ）
⑺ AC Frequency Code ————————————————– 50Hz is omitted here, 60Hz add letter H
⑻ Voltage Level Code ————————————————– G1 means 6-6.6kV voltage level，G2 means 10-11kV voltage level, the new high voltage level code will be deducted from this, and the low voltage code will be omitted.
☆1.2 Standard atmospheric conditions for generator testing and operation
Standard atmospheric conditions for generator operation（According to the standard.GB/T 2820.1）
Environmental temperature Tr：298K (25℃)
Absolute atmospheric pressure Pr：100kPa（Elevation 100m）
Relative humidity of air ￠r：30%
☆1.3 Description of generator power
According to the standard GB/T 2820.1, our company defines the power occupation of the generator as follows,
⑴ Prime Power（PRP）: It means that the generator can supply power to the load to the load for 12 hours under the predetermined service cycle and the predetermined environment, where there is an hour to operate at 100% rated power.
⑵ Standby Power（LTP）:It means that the generator operates according to the rated power indicated on the nameplate between the specified maintenance periods and under the specified environmental conditions. It is generally used in places with a reliable mains supply. When the mains supply is cut off, it provides standby power and has no overload capacity. It allows one hour of full-load operation every 12 hours on average and does not exceed 500 hours of full-load operation every year.
☆1.4 Method for estimating generator current
The formula for calculating the rated output current of the generator is as follows,
I is rated output current（A）；U线 is the line voltage of the generator（V）；cos￠is the power factor of the generator，its value is 0.8；P is the power of the generator (W).
※ For example：For rated voltages of 400/230V，The output power is 880kW generator，the rated output current is calculated as follows.
I≈（1000/×400×0.8）×880=1587.5（A）
☆1.5 Generator power correction
☆1.5.1 The importance of power correction
① If the environmental temperature is higher than 25℃, the atmospheric pressure is below than 100kPa，relative humidity is higher than 30%, the rated power of the generator shall be corrected. If the load power of the generator is greater than the rated power, the diesel engine will smoke and overheat. Such a long time running diesel engine will produce major failure and damage, please take everything lightly.
② When the ambient temperature is too high, the air density decreases, the amount of oxygen in the diesel engine combustion decreases, and the combustion efficiency decreases, which will reduce the mechanical output power of the diesel engine. At the same time, cold air needs to cool the winding when the alternator is working. When the ambient temperature is too high, the internal temperature of the generator is rising, in order to ensure the winding temperature of the alternator, it must also be reduced within the allowable range of the output power of the generator.
③ As the altitude rises, the air density will also decrease, which also affects the output power of diesel engines and alternators.
④ When the diesel generator is used under low-temperature conditions and in a high humidity area, although it does not cause a reduction in generator output power, it must also take into account the use of field conditions, and may affect the normal use of the generator factor.
⑤ Therefore, when the generator is used under non-standard environmental conditions, the user should modify it according to the conversion method of generator power. However, the influence of environmental conditions on the output power of different brands of generators is different, so the output power of different brands of generators changes with environmental conditions, and the revised parameters are different. The detailed correction factor can be consulted with the technical department of Weifang Junwei Machinery Co., Ltd.
☆1.5.2 Power correction calculation method
□ Corrected calculation of diesel engine output power：
N=Ne×α-Nf
Among.： N– Corrected power output of diesel engine under field conditions, kW
Ne— Diesel engine rated power,kW
Nf— The power consumption of diesel engine fan is generally 3% to 4% of the rated power of diesel engine
α– Total correction factor of diesel engine
□ Corrected calculation of output power of alternator.：
P=Pe×β
Among：P– Alternator, corrected output power under field conditions,kW
Pe— Alternator rated power.,kW
β– Correction factor of the alternator.
□ The power output of generator.：Ph
The output power of the alternator is the product of the net output power of the diesel engine N and the mechanical efficiency of the alternator, and the smaller value is compared with the alternator power P.
They are:
while N×η＞P，Ph=P；
while N×η＜P，Ph=N×η；
Among：η–The mechanical efficiency of the alternator
☆1.6 Diesel generator electrical performance
Suppress radio interference in accordance with VDEO875-N and GB2820.
