1: The generator does not operate according to the specified technical conditions, such as the stator voltage is too high, the iron loss increases; the load current is too large, the stator winding copper loss increases;
If the frequency is too low, the cooling fan speed will be slowed down, which will affect the heat dissipation of the generator. If the power factor is too low, the rotor excitation current will increase and the rotor will heat up. Check that the indication of the monitoring instrument is normal. If it is abnormal, necessary adjustments and treatments shall be carried out to make the generator run according to the specified technical conditions.
2: The three-phase load current of the generator is unbalanced, and the overloaded one-phase winding will overheat; if the difference between the three-phase currents exceeds 10% of the rated current, it is a serious phase-current imbalance, and the three-phase current imbalance will produce a negative Sequential magnetic field, thereby increasing losses, causing magnetic pole windings and ferrules and other components to heat up. 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 accumulation and poor ventilation, which makes it difficult for the generator to dissipate heat. The dust and grease on 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, the cooler is blocked. Reduce the inlet air or water temperature to clear the blockage in the cooler. Before the fault is eliminated, the generator load should be limited to reduce the generator temperature.
5: Too much or too little grease should be added to the bearing. Grease should be added according to regulations, usually 1/2 to 1/3 of the bearing room (the lower limit for the low speed and the lower limit for the high speed), and the bearing should not exceed 70% of the room is appropriate.
6: Bearing wear. If the wear is not serious, the bearing will overheat locally; if the wear is serious, the stator and rotor may be rubbed, causing the stator and rotor avoiding parts to overheat. The bearings should be checked for noise. If friction between the stator and rotor is found, stop the machine immediately for maintenance or replace the bearings.
7: The stator core insulation is damaged, causing a short circuit between the pieces, which causes the local eddy current loss of the core to increase and generate heat, and in severe cases, the stator windings can be damaged. Stop immediately for maintenance.
8: The parallel wires of the stator winding break, causing the current of other wires to increase and generate heat. Stop immediately for maintenance.