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Jul
02 2024Marine power is lower than land power, and the performance meets various standard requirements and is better than land power.
3. Voltage, frequency, speed, number of phases
In most cases, generator sets are used as backup or emergency power sources, or connected to the grid. The voltage frequency and phase number of the generator should depend on the power grid requirements of different countries and regions. For those without a power grid and using generators as the main power source, the voltage and frequency of the generator should be determined by its load condition, or the generator should be selected based on the load, or the voltage and frequency of the load should be selected based on the generator.
(1) Frequency: Generally, there are two types (power frequency): 50 or 60.
(2) Phase number: Generally, for commercial installations, it is 3 phases, and single-phase can be obtained from it.
(3) Voltage: The voltage is selected according to the specific requirements, and Stanford generators can provide and meet the voltage requirements of customers.
① Low voltage range: from 110 to 690V;
From 5 to 5, there are 12 leads to the terminal block, and customers can change the voltage according to their different connection methods and connect it to single-phase. For 5 or more, there are 6 leads to the terminal block, and the voltage can be changed according to the connection method.
② Medium voltage range: 2400-4160V;
③ High voltage range: 6000V~11KV.
(4) Speed
Usually divided into two types: 1500r/min and 1800r/min.
(5) The relationship between frequency, speed, and number of poles
F=(N×P) / 60
Among them: F is the frequency; N is the rotational speed RPM; P is the number of generator poles.
4. Power generation efficiency
The efficiency of a generator refers to the ratio of the output kilowatts (electrical energy) to the mechanical work input into the generator
That is, efficiency=(output power of generator output terminal)/mechanical power input to the generator
Therefore, the power input from the diesel engine to the generator shaft should be greater than or equal to the input power of the generator. This input power, excluding the connection efficiency between the diesel engine and the generator, should be the minimum output power of the diesel engine. The efficiency of a generator varies under different voltages and loads, as shown in the efficiency curve Figure 3 and performance gimbal Figure 4.
5. Temperature rise
Due to the copper loss, iron loss in the iron core, and other mechanical wear caused by the winding resistance of the generator, heat is generated during operation, causing an increase in the temperature of the generator winding and resulting in insulation aging or damage to the generator winding.
Cummins defined the relative rise in winding temperature of a generator as the temperature rise of the generator. The allowable temperature rise for various insulation levels based on an ambient temperature of 40 ℃ is listed in Table 1.
表1 发电机绝缘等级的最大允许温升表
绝缘等级 |
A |
B |
E |
F |
H |
最大允许温升 |
60℃ |
75℃ |
80℃ |
105℃ |
125℃ |
2、 Application environment
1. Relative humidity
(1) Humidity mainly refers to the content of moisture in the air, usually expressed as relative humidity.
(2) For areas with high humidity, we must carefully select the insulation and impregnation system of the generator to adapt to tropical climates.
(3) All Stanford generators can adapt to tropical climates.
2. Altitude
Due to the thinning of air at altitudes exceeding 1000 meters, and the fact that generators rely on fans for air cooling, the cooling effect of generators will deteriorate. Therefore, it is required to reduce the power of generators at altitudes exceeding 1000 meters to avoid overheating. But this does not mean that the generator power can increase when the altitude is below 1000 meters.
When exceeding 1000 meters, the actual output power of the generator should be multiplied by the correction factor in Table 2, and the power drop curve is shown in Figure 3.
Table 2 Correction Factors for Generators at High Altitude
海拔高度(M)
|
修正系数
|
1500
|
0.97
|
2000
|
0.94
|
2500
|
0.91
|
3000
|
0.85
|
3500
|
0.82
|
3. Environmental temperature
According to internationally recognized technical requirements, the operating environment temperature for generators is generally defined as 40 ℃, and all designs and power are based on this environmental temperature.
(1) In fact, for a generator, the ambient temperature should be the inlet air temperature of the generator. Due to the generator working together with the diesel engine, the heating of the diesel engine can cause the temperature in the entire space to exceed 40 ℃. The ambient temperature of the generator during actual operation should not exceed 40 ℃, which is very important. If the actual operating environment temperature exceeds 40 ℃, the generator should operate at reduced power.
(2) For the ambient temperature, if it is below 40 ℃, the power of the generator can be higher than the rated power. When the ambient temperature exceeds 40 ℃, the power correction coefficient of the generator is listed in Table 5, and the power decrease curve is shown in Figure 6.
表3 高温环境下发电机修正系数表
环境温度(℃) |
系数 |
45 |
0.97 |
50 |
0.94 |
55 |
0.91 |
60 |
0.88 |
图5 高海拔下发电机功率降低曲线 |
图6 高温下发电机功率降低曲线 |
4. Special climate and environment