Temperature rise requirements and cooling methods for diesel generator sets

As an emergency power source, diesel generator sets need to operate continuously for extended periods. Given such a heavy load, the temperature of the generator sets becomes a challenge. To maintain good uninterrupted operation, it is necessary to keep the temperature of the generator sets within an acceptable range. This requires everyone to understand the temperature rise requirements and cooling methods.
1: Temperature rise requirements
Based on the different insulation levels of diesel generators, their temperature rise requirements vary. Generally, when a generator is in operation, the temperature of its stator winding, excitation winding, iron core, collector ring, etc. is about 80 degrees Celsius. If it exceeds 80 degrees Celsius, it is considered to have an excessively high temperature rise.
II: Cooling method
Generators of different types and capacities have varying cooling methods. However, the cooling mediums commonly used are air, hydrogen, and water. Taking the turbo-synchronous generator as an example, its cooling system is enclosed, and the cooling medium is recycled.
(1) Air cooling
Air cooling is achieved by using fans to blow cold air onto the ends of the generator windings, as well as the stator and rotor of the generator set, to dissipate heat. After absorbing heat, the cold air turns into hot air, which initially converges between the stator and rotor before being discharged through the air ducts of the iron core and then cooled by the cooler. The cooled air is then blown back into the generator by the fan for internal circulation and heat dissipation. Medium and small-sized synchronous generators generally adopt air cooling.
(2) Hydrogen cooling
Hydrogen cooling utilizes hydrogen as the cooling medium, and hydrogen has better heat dissipation performance than air. For example, most turbo-generators are cooled using hydrogen.
(3) Water cooling
The water cooling system employs a dual internal water cooling approach for both the stator and rotor. The external water system of the stator water system flows through water pipes to the inlet rings mounted on the stator frames, and then through insulation tubes to each coil, where it absorbs heat. Afterwards, it flows through insulation water pipes to the outlet rings mounted on the machine base, and is then discharged into the external water system of the generator for cooling. The cooling process of the rotor water system begins with water entering the inlet support mounted on the shaft end of the exciter side, then flowing into the central hole of the rotating shaft, and then flowing through several radial holes to the water collection tank, and then through insulation tubes to each coil. After absorbing heat, the cold water flows through insulation tubes into the water outlet tank, and then through the drainage holes on the outer edge of the water outlet tank to the water outlet support, and is led out by the main water outlet pipe. Since the heat dissipation performance of water is much higher than that of air and hydrogen, newly built large generator sets generally adopt water cooling methods.