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The estimation of the capacity of common diesel generator sets requires consideration of various factors
July 06, 2022
When buying a diesel generator set, the capacity must be carefully determined, if the capacity of the unit is selected too small, it will not be able to drive all the load or in the start of high-power load, resulting in a sudden shutdown phenomenon; if the capacity of the unit is selected too large, the investment and maintenance costs are high, resulting in a waste of resources. And according to the characteristics of diesel engine, when it works under small load for a long time, it will cause serious carbon accumulation in the engine piston ring, oil injection nozzle, etc., and the cylinder wear will increase and damage the unit.
Diesel generator set
Commonly used diesel generator sets are in a certain period of time or often need to run continuously for a long time, in order to be used as a common power supply for the electricity load, often used away from the large power grid of the township, island, forestry, mining, oil fields and other areas, in general, commonly used diesel generator set capacity estimates according to the unit long-term continuous operation output power can meet the maximum calculated load of the whole project to choose, and should be based on the importance of load Determine the capacity of the backup unit, in addition, commonly used diesel generator sets in the capacity estimation also need to consider a number of factors including the use of environment, load type and reserve margin.
First, the use of the environment
The use of the environment mainly includes: ambient temperature, altitude and relative air humidity. Different use of the environment will affect the output power of diesel generator sets. When the ambient temperature, altitude is too high, the air density is reduced, the supply of oxygen required for combustion when the unit is running is reduced, the output power of the unit should be adjusted downward accordingly. In other words, the selected power of the unit should be higher than the power value of the load, that is, when the unit works in non-standard conditions, the diesel engine should be corrected for power.
It is worth noting that: electronic injection diesel engine adopts electronic injection control technology, through the electronic control unit installed on the diesel engine to accurately measure the intake manifold intake pressure, fuel temperature and other parameters, in order to control the injection timing and injection volume of each injector, which makes the power of the unit drop less under non-standard conditions.
Second, the type of load
Different types of loads vary greatly in their requirements for generator set capacity. Load types are generally divided into resistive loads, inductive and other linear loads and non-linear loads containing rectifier circuits (also known as rectified loads).
Resistive loads: light bulbs, electric stoves and ovens, etc.
Inductive loads: air conditioners, machine tools and water pumps, etc.
Non-linear loads: UPS, electronic computers, program-controlled switches and PLC equipment, etc.
The characteristic of resistive load is that the resistance remains basically constant and the current decreases proportionally with the voltage, so when carrying this kind of load, the capacity of the generator set can be slightly larger than the load power. However, when carrying inductive loads and non-linear loads, the capacity of the generator set needs to be recalculated. In calculating the capacity of the generator set, the performance of each load should be clear in order to make the right choice.
Third, other considerations
After calculating the capacity of the unit according to the existing load, other factors should be considered, whether there is the possibility of expanding the load after today, whether some loads may occur overload phenomenon, etc.. It is suggested that the capacity of the unit should be increased appropriately according to the actual situation. In addition, where economic conditions permit, it is recommended to use two or more generator sets, some of which are used for sensitive loads (such as electronic computer systems and other electronic equipment) and others for insensitive loads (such as resistive loads and electric motors), in order to prevent the impact on sensitive loads due to the distortion of the unit voltage waveform caused by the motor starting.
When buying a diesel generator set, the capacity must be carefully determined. If the capacity of the set is chosen too small, it will not be able to drive all the loads or cause sudden shutdown when starting high-power loads; if the capacity of the set is chosen too large, the investment and maintenance costs will be high, resulting in a waste of resources. Moreover, according to the characteristics of diesel engine, when it works under small load for a long time, it will cause serious carbon accumulation in the engine piston ring and oil injection nozzle, and the cylinder wear will be increased, which will damage the unit. On the choice of capacity, it is recommended that users should directly consult professional generator manufacturers.
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