The overheating analysis of the generator fault type is as follows:
(1) The generator does not operate according to the specified technical conditions. For example, the stator voltage is too high and iron loss increases. ; the load current is too large and the copper of the stator winding is too low, which slows down the speed of the cooling fan and affects the heat dissipation of the generator, the power factor is too low, which increases the current excites the rotor and causes the rotor to heat up. Check whether the monitoring instrument indication is normal. If this is abnormal, necessary adjustments and treatments should be made to operate the generator according to the specified technical conditions.
(2) The three-phase load current of the generator is unbalanced, and the overloaded single-phase winding will overheat if the difference between the three-phase current exceeds 10% of the current.nominal current; This is a serious phase current imbalance. Unbalanced three-phase current will produce a reverse magnetic field, thereby increasing losses and causing heating of components such as pole windings and ferrules. The three-phase load must be adjusted to keep the current in each phase as balanced as possible.
(3) The air duct is clogged with dust and ventilation is poor, making it difficult for the generator to dissipate heat. Dust and grease in the air duct must be removed so that the air duct is not clogged.
(4) The inlet air temperature is too high or the inlet water temperature is too high and the chiller is blocked. The inlet air or water temperature must be lowered to eliminate blockage in the cooler. Before the fault is cleared, the generator load must be limited toto reduce the generator temperature.
(5) Too much or too little grease is added to the bearing. Grease should be added according to regulations, generally 1/2 to 1/3 of the bearing chamber (the upper limit is used for low temperatures). (and the upper limit is used for high speeds). Lower Limit) and shall not exceed 70% of the bearing chamber.
(6) Bearing wear. If wear is not significant, the bearing may overheat locally; if wear is severe, the stator and rotor may rub against each other, causing the stator and rotor to overheat. Bearings should be checked for noise. If friction between the stator and rotor is detected, the machine should be stopped immediately for maintenance or replacement of the bearings.
(7) The insulation of the stator core is damaged, causing a short circuit between the parts, resulting inan increase in local eddy current losses and heat generation. In severe cases, the stator winding will be damaged. . The machine must be stopped immediately for maintenance.
(8) The parallel wire of the stator winding is broken, causing the current of other wires to increase and generate heat. The machine must be stopped immediately for maintenance.