Judgment and analysis of rotor inter-turn short circuit of hydroelectric turbine generator:
Rotor inter-turn short circuit is one of the common faults of hydroelectric turbine generator, which is very detrimental to the safe operation of the generator. There are two situations of inter-turn short circuit: one is that it occurs shortly after the generator is switched on. When the generator is not loaded or the load is very light, an inter-turn short circuit occurs. The phenomenon is smoke. coming out of the pit and the insulation. Burnt smell. The other is an inter-turn short circuit that occurs after long-term operation of the generator. There are many reasons, such as poor manufacturing process, improper operation and maintenance, metal shavings or dust falling on the stator winding, etc. -short circuit if not cleaned for a long timegue period, it is also possible for small animals like rats to crawl into the stator chamber and cause a short circuit between the turns.
For the first case, when a short circuit between turns occurs, due to a very light or no load, the changes in stator voltage and current are not obvious (the voltage of power supply is normal), but there is smoke in the pit, and there is a smell of burnt insulation. Service personnel should measure and inspect the generator with voltage transformers, current transformers and instruments according to the load of the generator, whether there is smoke or odor in the pit and whether the noise of the generator is abnormal, etc. Differential protection to eliminate faults. Where conditions permit, two-in-one protection (overcurrent, undervoltage and overvoltage) should also be used to clear faults. When conditions are notIf met, the generator's emergency protection can clear the fault.
For the second case, when a short circuit between turns occurs, this is due to a large load or full load. The stator voltage and current will change significantly. The stator current increases and the voltage decreases. At this point, the generator load should be reduced immediately and the duty manager and electrical branch manager should be reported promptly. After seeking permission from the chief engineer, biotechnology department and dispatching officials, disconnect the excitation switch and uncouple the generator to shut it down. When conditions permit, external inspection and measurements should be carried out as much as possible to accurately locate the fault point. For example, the current value and the voltage variation of the short circuit between turns can be measured, and theUnbalanced magnetic pull force can be measured. When you are sure that the generator can continue to operate. Generators must be operated in conjunction with the approval of the reporting official. When the conditions are not met. The fault must be resolved by generator backup protection.
What is the reason for the sudden increase in the incoming line voltage of the generator? I sincerely ask for advice.
No-load test, overspeed test and inspection of hydraulic turbine generator set?
1. Disconnect each overspeed protection contact of the speed measuring device from the water machine protection circuit and use temporary methods to monitor its action.
2. Manually bring the unit up to rated speed; Once the unit is operating normally, continue to increase the opening of the opening limiting mechanism bys guide vanes to increase unit speed to 115% of rated speed. Observe the action of the contacts of the speed measuring device.
3. If the unit operates without malfunction, continue to increase the speed to the overspeed protection setting value specified in the design and monitor the action of the electrical and mechanical overspeed protection devices.
4. During the overspeed test, the swing and vibration values of each part should be closely monitored and recorded, the temperature increase of each bearing and the change of the generator air gap should be recorded. , and if there are abnormal sounds should be monitored.
5.Once the overspeed test is stopped, the following inspections should be carried out:
1) Complete inspection of the rotating parts of the generator, such as the yoke keys of the generator rotor, the keys ofs magnetic poles, damping rings, cable poles, yoke pressing screws, etc., for play or offset.
2) Check the condition of the generator stator foundation and upper frame cylinder.
3) Adjust the overspeed protection device if necessary.
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Generator incoming line voltage? The generator supplies voltage and current to the load. This should be the outgoing wire. Why is this the incoming wire? If the voltage suddenly increases, assuming you mean the output voltage increases, it also depends on whether the generator is an independent load or connected to the grid.water, as well as generator excitation regulation performance. The generator voltage is increased by excitation of the rotor. When the generator output voltage meets the power conditions, the load is turned on. Due to the impedance drop in the generator winding, the output voltage undergoes a voltage reduction process. The generator has strong excitation regulation ability (this process is very short or cannot be felt by humans). Similarly, when the load is suddenly disconnected, the output voltage of the generator suddenly increases. a diesel engine) will increase and the voltage will be higher. The diesel engine should also have a quick speed adjustment function. For example, a water turbine generator is designed with water resistance to prevent load shedding from increasing the rotational speed, and the water resistance is automatically implemented when loadis relieved.