How Does A High/Low Temperature Dry Cooler Work in A Generator?
How Does a High/Low Temperature Dry Cooler Work in a Generator?
To Cool Generator Windings
Prevent overheating damage
Generator in the operation process, the current through the stator and rotor windings will produce a lot of heat. If this heat can not be emitted in time, the temperature of the winding will rise sharply. For example, for large generators, when the temperature of the windings exceeds the limit temperature that the insulation material can withstand (generally about 130 - 150 ℃, depending on the insulation grade), the insulation material will accelerate the aging, the insulation performance will be reduced, and may even lead to short-circuit failure. The high and low temperature dry cooler can circulate the cooling medium to take away the heat generated by the windings, control the temperature of the windings within the safe range, and extend the service life of the generator.
Maintaining good electrical performance
The right temperature also has an effect on the resistance of the generator windings. According to the law of resistance (where is resistance, is resistivity, is the length of the conductor, is the cross-sectional area of the conductor, is the temperature coefficient of resistance, is the change in temperature), an increase in temperature will result in an increase in winding resistance. Excessive resistance will increase the generator's copper loss (, where is the copper loss power, is the current) and reduce the generator's efficiency. High and low temperature dry cooler can maintain the winding temperature at a relatively stable level to ensure that the winding resistance is in a reasonable range, so as to ensure that the electrical performance of the generator is stable and improve power generation efficiency.
Cooling the Generator Iron Core
Reduce hysteresis loss and eddy current loss
Generator iron core is made of silicon steel sheet stacked, under the action of the alternating magnetic field will produce hysteresis loss and eddy current loss. These losses will be converted into heat, so that the core temperature increases. Hysteresis loss is proportional to the magnetic field frequency, core volume and hysteresis loop area; eddy current loss is proportional to the square of the magnetic field frequency, the square of the maximum flux density of the core and the core volume. These losses are further increased when the core temperature rises. The high and low temperature dry cooler can cool the iron core and reduce the iron core temperature, thus reducing the hysteresis loss and eddy current loss and improving the energy conversion efficiency of the generator.
Prevent core deformation
High temperatures may cause deformation of the iron core due to thermal expansion. If the iron core is deformed, it will affect the air gap magnetic field distribution of the generator. The unevenness of the air gap magnetic field will cause vibration and noise increase of the generator, and also reduce the output voltage and power quality of the generator. High and low temperature dry cooler can effectively control the iron core temperature, prevent iron core deformation, and ensure the stable operation of the generator.
Control the Humidity of Generator Internal Environment
Prevent condensation and corrosion
If the humidity inside the generator is too high, condensation is likely to occur on the surface of the components at lower temperatures. The water droplets formed by condensation may drip down to the electrical components of the generator, such as windings, iron core, terminals, etc., resulting in short circuit or corrosion. The high and low temperature dry cooler can reduce the humidity inside the generator by circulating the dry cooling medium during the cooling process, avoiding the occurrence of condensation and corrosion and ensuring the reliability of the electrical equipment inside the generator.
Maintenance of insulation performance
Humidity has a great impact on the insulation performance of generators. High humidity environments can cause insulating materials to absorb moisture and reduce their insulation resistance. For example, when the humidity inside a generator exceeds a certain limit, the surface resistivity of the insulating material may drop from hundreds of megohms to a few megohms or even less. This can greatly increase the risk of insulation breakdown in a generator. High and low temperature dry coolers help to maintain good generator insulation by controlling humidity.
