Common faults of motors and effective treatment methods
Due to insufficient compensation of the excitation excitation of the voltage source of the excitation device, the excitation current required for the armature reaction cannot be provided, so that the generator terminal voltage is lower than the grid voltage and the rated reactive power cannot be delivered. The following measures should be taken:
1: Connect a three-phase voltage regulator between the generator and the excitation reactor to increase the voltage at the generator terminal and increase the magnetic potential of the excitation device.
2: Change the phase of the magnetomotive force of the excitation device and the voltage of the generator terminal to increase the total magnetomotive force. The resistance of several thousand ohms and 10W can be connected in parallel at the two ends of each phase winding of the reactor.
3: Reduce the resistance of the varistor to increase the excitation current of the generator.
6. Stator winding insulation breakdown, short circuit
1: The stator winding is damp. For generators that have been deactivated for a long time or have been repaired for a long time, the insulation resistance should be measured before putting into operation. Those who fail are not allowed to put into operation. The damp generator should be dried.
2: Defects in the winding itself or improper maintenance process, resulting in insulation breakdown or mechanical damage of the winding. The insulation material should be selected according to the specified insulation grade, and the embedded winding and the dipping paint should be strictly in accordance with the process requirements.
3: The winding is overheated. When the insulation is overheated, the insulation performance is lowered, and sometimes the insulation breakdown is quickly caused at a high temperature. Daily inspections should be strengthened to prevent overheating of various parts of the generator and damage the winding insulation.
4: Insulation aging. Generally, the generator runs for 15 to 20 years, and its winding insulation is aging, electrical properties change, and even insulation breakdown. To do the maintenance and preventive test of the generator, if the insulation is found to be unqualified, replace the defective winding insulation or replace the winding in time to prolong the service life of the generator.
5: The inside of the generator enters the metal foreign matter. After repairing the generator, do not leave the metal objects, parts or tools in the stator ;; tie the tying line of the rotor and fasten the end parts so as not to occur due to centrifugal force. Loose.
Excessive voltage breakdown:
1. The line is struck by lightning and the lightning protection is not perfect. Lightning protection facilities should be improved.
2. Misoperation, such as when the load is too high, the generator voltage is raised too high. The generator should be boosted in strict accordance with the operating procedures to prevent misuse.
3. The internal overvoltage of the generator, including the operating overvoltage, arc grounding overvoltage and resonant overvoltage, etc., should strengthen the winding insulation preventive test, and find and eliminate the defects in the stator winding insulation in time.
Stator core relaxation:
The core is not fastened due to improper manufacturing and assembly. If the entire core is slack, for a small generator, two iron plates smaller than the inner diameter of the end of the stator winding can be used, and the studs can be put on and the core can be tightened. After the original shape is restored, the original clamping bolt of the iron core is tightened. If the local core is slack, first apply a silicon steel sheet paint between the slack sheets, and then insert a hard insulating material into the slack.