How to diagnose and eliminate generator overheating faults
During the operation of the generator, overheating may occur occasionally. How should this overheating be diagnosed, and what methods should be adopted to eliminate the problem? Here are the details: The generator is not operating according to the standard technical conditions, such as excessive stator voltage, increased iron losses; excessive load current, increased copper losses in the stator winding; low frequency, slowing down the cooling fan speed, affecting the generator's heat dissipation; and low power factor, increasing the excitation current of the rotor, causing the rotor to overheat.
Ensure the instructions for supervising the external appearance are normal. If not, necessary adjustments and treatments should be carried out to ensure the generator operates according to the specified technical conditions. An unbalanced three-phase load current in the generator will cause the overloaded phase winding to overheat; if the difference in three-phase current exceeds 10% of the rated current, it is considered a severe phase current imbalance. Unbalanced three-phase current will generate a negative sequence magnetic field, subsequently increasing losses and causing the magnetic pole winding and sleeve, among other components, to overheat. Adjust the three-phase load to maintain as much balance as possible among the phases.
The air ducts are blocked with dust, leading to poor ventilation and difficulty in dissipating the generator's heat. The accumulated dust and oil should be removed to ensure the air ducts are unobstructed. If the intake air temperature is too high or the intake water temperature is too high, the cooler shows signs of blockage. The intake or water temperature should be reduced to clear the blockages inside the cooler. Before the issue is resolved, the generator load should be restricted to lower the generator temperature.
Excessive or insufficient lubricant in bearings should be added according to regulations, generally 1/2 to 1/3 of the bearing chamber (for low-speed bearings, take the upper limit; for high-speed bearings, take the lower limit), and it's advisable not to exceed 70% of the bearing chamber. Bearing wear. If the wear is not severe, it may cause the bearing to overheat partially; if the wear is severe, it could lead to stator and rotor collision, resulting in overheating of the stator and rotor avoidance sections. Check for bearing noise; if stator and rotor collision is detected, immediately shut down and conduct maintenance or replace the bearings.
