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Users must understand the causes of overheating of diesel generator sets

June 14, 2022
The operating temperature of diesel generator sets has strict standards. If the temperature is too high or too low, it will cause damage to the unit to varying degrees. Some users think that the overheating of diesel generator sets usually occurs in hot summer. Now that the temperature is low, there is no need to worry. In fact, this is very wrong. There are many reasons for the overheating of diesel generator sets, and the environmental climate is only one of them. Users must keep in mind the following reasons for the overheating of diesel generator sets, so as to take cooling measures in time to reduce unit failures.
1. The diesel generator set does not operate according to the specified technical conditions. For example, if the stator voltage is too high, the iron loss will increase; if the load current is too large, the copper loss of the stator winding will increase; if the frequency is too low, the speed of the cooling fan will be slowed down, which will affect the generator. Heat dissipation; the power factor is too low, which increases the rotor excitation current and causes the rotor to heat up. It should be checked whether the indication of the monitoring instrument is normal. If it is not normal, make necessary adjustments and treatments to make the generator operate in accordance with the specified technical conditions.
2. The three-phase load current of the diesel generator is unbalanced, and the overloaded one-phase winding will overheat; if the difference between the three-phase current exceeds 10% of the rated current, it is a serious phase current imbalance, and the three-phase current imbalance will produce Negative sequence magnetic field, thereby increasing losses and causing heating of components such as pole windings and ferrules. The three-phase load should be adjusted to keep the current of each phase as balanced as possible.
3. The air duct is blocked by dust, and the ventilation is poor, which makes the diesel generator difficult to dissipate heat. The dust and grease in the air duct should be removed to make the air duct unobstructed.
4. The inlet air temperature is too high or the inlet water temperature is too high, and the cooler is blocked. The inlet air or inlet water temperature should be lowered to clear blockages in the cooler. Before the fault is eliminated, the generator load should be limited to reduce the generator temperature.
5. If there is too much or too little grease added to the bearing, grease should be added according to the regulations, usually 1/2 to 1/3 of the bearing chamber (the upper limit for the low speed and the lower limit for the high speed), and should not exceed the bearing chamber. 70% of the room is appropriate.
6. Bearing wear. If the wear is not serious, the bearing will be overheated locally; if the wear is serious, it may cause friction between the stator and the rotor, causing the stator and the rotor to overheat. The bearing should be checked for noise. If friction between the stator and the rotor is found, it should be stopped immediately for maintenance or replacement of the bearing.
The above are the reasons that easily lead to overheating of diesel generator sets. I hope to help you. If you encounter serious failures caused by overheating of the generator set, please contact professional maintenance personnel for on-site maintenance in time, and do not disassemble and assemble the generator set without authorization!