1. Generator overheating
(1) The generator does not operate according to the specified technical conditions. If the stator voltage is too high, iron loss increases; copper loss from the stator winding increases; the frequency is too low, slowing down the speed of the cooling fan and affecting the heat dissipation of the generator; the power factor is too low, which increases the rotor excitation current 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 rated current, it will This is a current imbalanceSevere phase and three-phase current imbalance will produce a reverse magnetic field, thereby increasing losses and causing heating of magnetic pole windings, ferrules and other components. 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 to reduce the generator temperature.ur.
(5) Too much or too little grease should be added to the bearing. Grease should be added according to regulations, generally 1/2 ~ 1/3 of the bearing chamber (the upper limit is used for). low speed, and the upper limit is used for high speed). lower limit), and must not exceed 70% of the bearing chamber.
(6) Bearing wear. If the wear is not significant, the bearing will 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 in increased eddy current lossest local 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.
2. There is abnormal voltage between the neutral line of the generator and the earth
(1) Under normal circumstances, the air under each magnetic pole is caused by the influence of high order harmonics or manufacturing process. Very low voltage occurs due to uneven gaps and uneven magnetic potential. If the voltage is one to several volts, there is no danger and there is no need to deal with it.
(2) The generator winding has a short circuit or poor insulation from ground, causing the performance of the generator to deteriorate.electrical equipment and generator and easily generates heat. It must be repaired in time to avoid expansion. of the accident.
(3) There is no voltage between the neutral line and earth when there is no load, but voltage appears when there is a load. This is caused by the imbalance of the three phases. the phase load must be adjusted to make it fundamentally balanced.
3. Generator current is too large
(1) The load is too large and the load should be reduced.
(2) If a phase short circuit or ground fault occurs in the transmission line, the line should be inspected and repaired after the fault is cleared. Can return to normal.
4. The voltage across the generator is too high.
5. Insufficient power
There are several reasons why the temperature of various parts of the generator increases:
1. The three-phase currentstator assembly is unbalanced;
2. The flow rate and temperature of the cooling water are abnormal;
3. Generator The air path is blocked or the air cooler is cut off and the water temperature is too high, making the temperature of looks abnormal;
4.
The treatment method when the above reasons occur is as follows:
1. Strictly monitor the imbalance current of the three-phase stator and must not exceed regulations;
2. Adjust the pressure, flow and temperature of the internal cooling water system; > 3. If it is found that air enters the rotor coil, the cooling water flow decreases and the temperature increases abnormally, the machine should be stopped for treatment;
4; . Increase the amount of water in the air cooler or pour in additional water.