Loose connection loose connection can also be included in the lack of maintenance, this category includes the manufacturing process in the electrical connection and maintenance, one is the improper cooperation between the different nature of the metal, despite this phenomenon in recent years Reduced. The second is improper fastening of bolted joints.
Troubleshooting of Common Faults Symptoms and Troubleshooting on Windings a. When the transformer abnormally heats up, the oil temperature rises, the oil emits a special hum, the power supply side current rises, the three-phase DC resistance is different, but the difference is small. The fuse is blown, the fall insurance falls off, the oil pillow is covered with black smoke, and when the gas relay is in motion, it is a short circuit between windings. We can add 10% 20% voltage to the windings. The smoke at the windings is the short circuit between the windings. Then you can rewind the coil to solve the problem.
b, serious short-circuit between the layers, and the difference between the three-phase DC resistance is obvious, you can determine the phase of the short circuit between the layers through DC resistance measurement, and then rewind the coil. c. High-voltage fuses are blown, the airway diaphragm ruptures, fuel injection, and gas relays operate. Small transformer tanks without safety airways and gas relays are judged to be short-circuited to earth and short-circuited when they are deformed and destroyed. At this time, the fault phenomenon is very serious. Obviously, the consequences are serious and the coils should be rewired immediately after the power outage. d. When there is an electric arc at the disconnection to make the transformer discharge and there is no current in the disconnected phase, it is judged that the winding coil is disconnected and the core must be removed. If it is caused by a short circuit, the coil should be rewinded. If the lead breaks, Reconnect.
Iron core problems and exclusion methods a, there is no load large fuel consumption, oil temperature, oil darker, hanging core inspection can see the film off, some of the silicon steel exposed, brittle, blistering and discoloration due to insulation carbonation When it is darkened, it should be checked. The restoration insulation is coated on the both sides of the core laminations with paint No. 1611 or No. 1030. The thickness of the paint film is 0.010.015 mm after drying.
b. High-voltage fuses are blown, the oil is blackened and has a special odor. When the temperature rises, the hanging core can see the hot spots of the silicon steel sheet. When the insulation damage becomes hot, the welding point is eliminated by the hanging core, and the insulation of the feed screw is restored, or Eliminate extra ground points. c. Abnormal noises that are different from normal snoring sounds may be abnormal sounds of copper. You can try to clamp the clips or re-laminate them to eliminate the cause of the ringing.
The phenomenon of oil problems and how to eliminate them The oil color of the transformer darkens. It may be that the oil quality is deteriorated. It can be checked regularly and it is decided to filter or change the oil. Problems caused by tap-changer problems and remedies a. When a high-voltage fuse is blown, a smoke from a grease pillow, and a hum of transformer oil are issued, it is determined that the contacts between the phases are discharged or the tap discharges. The tap changer can be turned regularly for a few weeks after a power failure to make good contact. b. When the oil temperature rises, the high-voltage fuse blows, and the surface of the contact produces a discharge sound, it is judged that the surface of the contact is melted and burned, and the tap changer can also be turned for a few weeks to make good contact after a periodic power failure.
Casing problem caused by the phenomenon and troubleshooting a, high-voltage fuse melting, may be a breakdown of the ground, can be observed during the inspection and timely detection of cracks, remove contamination, replace the casing. b. The high-voltage fuse is blown. It may also be caused by the discharge between the bushings. It is also necessary to replace the bushing.
Faults in the operation of the power transformer in the case of problems a, transformer insulation oil dielectric loss test failure, tg = 4.631% insulation oil degradation. b. Transformer differential protection action, high and medium voltage side tripping. When the main transformer low-voltage side switch is pulled open, three-phase grounding is shorted and the differential protection trips. c. The terminal at the top of the neutral point arrester of transformer 110kv side is melted. When the wiring is completed, the contact surface is in poor contact. d. The top terminal of the transformer neutral point 110kv neutral point arrester is damaged, and the action counter bursts.
Solution a. During the test, it was found that the loss factor of insulating oil medium was tg = 4.631%, which was obviously exceeded. Measured by mechanical oil filtration, it is still exceeding the standard and there is no change. The laboratory analysis determined that it contained alkyd resin components because the curing process of the insulating paint did not meet the requirements. Alkyd resin components in the operation gradually infiltrated into the insulating oil caused by, and then with the FY-6000 molecular sieve oil filter oil filter, 988 adsorbent adsorption alkyd resin method, tg reached 0.713%, the tracking test is relatively stable. Using this method can save more than 400,000 yuan compared to the method of replacing the insulating oil.
This problem is hidden in the process of installation and inspection. b, when operating the main transformer low-voltage side of the knife gate, open the knife gate, linkage knives after the knife, the knife gate moving contact bounce, causing the fracture distance is not enough to break through, causing three-phase short circuit, resulting in main transformer differential protection Action trip. Upon inspection, this accident was caused by the unreasonable design and manufacture of knife gates by the manufacturer. The replacement of the knife gate with the same type of knife gate can make the accident no longer occur.
End (1) Information should be widely collected and products with reasonable design, good manufacturing quality, and reliable operation should be used.
(2) Equipment installation and maintenance should be strengthened in the construction process management and strict implementation of the three-tier acceptance system. To solve the hidden problems in the construction before the equipment is put into operation, take preventive measures.
(3) In operation management, the switching operation shall strictly follow the procedures and strictly perform the correct operation.
Transformers are one of the important devices in the power grid. Although there are multiple protections such as arresters, differentials, and grounding, the accident rate is still high because of complex internal structures, uneven electric fields and thermal fields, and even malignant accidents and heavy losses. Therefore, drawing on foreign experience, using advanced online monitoring equipment to strengthen the state maintenance mode, so that the power supply is more secure and reliable.
Troubleshooting of Common Faults Symptoms and Troubleshooting on Windings a. When the transformer abnormally heats up, the oil temperature rises, the oil emits a special hum, the power supply side current rises, the three-phase DC resistance is different, but the difference is small. The fuse is blown, the fall insurance falls off, the oil pillow is covered with black smoke, and when the gas relay is in motion, it is a short circuit between windings. We can add 10% 20% voltage to the windings. The smoke at the windings is the short circuit between the windings. Then you can rewind the coil to solve the problem.
b, serious short-circuit between the layers, and the difference between the three-phase DC resistance is obvious, you can determine the phase of the short circuit between the layers through DC resistance measurement, and then rewind the coil. c. High-voltage fuses are blown, the airway diaphragm ruptures, fuel injection, and gas relays operate. Small transformer tanks without safety airways and gas relays are judged to be short-circuited to earth and short-circuited when they are deformed and destroyed. At this time, the fault phenomenon is very serious. Obviously, the consequences are serious and the coils should be rewired immediately after the power outage. d. When there is an electric arc at the disconnection to make the transformer discharge and there is no current in the disconnected phase, it is judged that the winding coil is disconnected and the core must be removed. If it is caused by a short circuit, the coil should be rewinded. If the lead breaks, Reconnect.
Iron core problems and exclusion methods a, there is no load large fuel consumption, oil temperature, oil darker, hanging core inspection can see the film off, some of the silicon steel exposed, brittle, blistering and discoloration due to insulation carbonation When it is darkened, it should be checked. The restoration insulation is coated on the both sides of the core laminations with paint No. 1611 or No. 1030. The thickness of the paint film is 0.010.015 mm after drying.
b. High-voltage fuses are blown, the oil is blackened and has a special odor. When the temperature rises, the hanging core can see the hot spots of the silicon steel sheet. When the insulation damage becomes hot, the welding point is eliminated by the hanging core, and the insulation of the feed screw is restored, or Eliminate extra ground points. c. Abnormal noises that are different from normal snoring sounds may be abnormal sounds of copper. You can try to clamp the clips or re-laminate them to eliminate the cause of the ringing.
The phenomenon of oil problems and how to eliminate them The oil color of the transformer darkens. It may be that the oil quality is deteriorated. It can be checked regularly and it is decided to filter or change the oil. Problems caused by tap-changer problems and remedies a. When a high-voltage fuse is blown, a smoke from a grease pillow, and a hum of transformer oil are issued, it is determined that the contacts between the phases are discharged or the tap discharges. The tap changer can be turned regularly for a few weeks after a power failure to make good contact. b. When the oil temperature rises, the high-voltage fuse blows, and the surface of the contact produces a discharge sound, it is judged that the surface of the contact is melted and burned, and the tap changer can also be turned for a few weeks to make good contact after a periodic power failure.
Casing problem caused by the phenomenon and troubleshooting a, high-voltage fuse melting, may be a breakdown of the ground, can be observed during the inspection and timely detection of cracks, remove contamination, replace the casing. b. The high-voltage fuse is blown. It may also be caused by the discharge between the bushings. It is also necessary to replace the bushing.
Faults in the operation of the power transformer in the case of problems a, transformer insulation oil dielectric loss test failure, tg = 4.631% insulation oil degradation. b. Transformer differential protection action, high and medium voltage side tripping. When the main transformer low-voltage side switch is pulled open, three-phase grounding is shorted and the differential protection trips. c. The terminal at the top of the neutral point arrester of transformer 110kv side is melted. When the wiring is completed, the contact surface is in poor contact. d. The top terminal of the transformer neutral point 110kv neutral point arrester is damaged, and the action counter bursts.
Solution a. During the test, it was found that the loss factor of insulating oil medium was tg = 4.631%, which was obviously exceeded. Measured by mechanical oil filtration, it is still exceeding the standard and there is no change. The laboratory analysis determined that it contained alkyd resin components because the curing process of the insulating paint did not meet the requirements. Alkyd resin components in the operation gradually infiltrated into the insulating oil caused by, and then with the FY-6000 molecular sieve oil filter oil filter, 988 adsorbent adsorption alkyd resin method, tg reached 0.713%, the tracking test is relatively stable. Using this method can save more than 400,000 yuan compared to the method of replacing the insulating oil.
This problem is hidden in the process of installation and inspection. b, when operating the main transformer low-voltage side of the knife gate, open the knife gate, linkage knives after the knife, the knife gate moving contact bounce, causing the fracture distance is not enough to break through, causing three-phase short circuit, resulting in main transformer differential protection Action trip. Upon inspection, this accident was caused by the unreasonable design and manufacture of knife gates by the manufacturer. The replacement of the knife gate with the same type of knife gate can make the accident no longer occur.
End (1) Information should be widely collected and products with reasonable design, good manufacturing quality, and reliable operation should be used.
(2) Equipment installation and maintenance should be strengthened in the construction process management and strict implementation of the three-tier acceptance system. To solve the hidden problems in the construction before the equipment is put into operation, take preventive measures.
(3) In operation management, the switching operation shall strictly follow the procedures and strictly perform the correct operation.
Transformers are one of the important devices in the power grid. Although there are multiple protections such as arresters, differentials, and grounding, the accident rate is still high because of complex internal structures, uneven electric fields and thermal fields, and even malignant accidents and heavy losses. Therefore, drawing on foreign experience, using advanced online monitoring equipment to strengthen the state maintenance mode, so that the power supply is more secure and reliable.
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