Distribution transformers often experience overheating during daily operation. Longer overheating time will cause the transformer to burn out and directly threaten the safe operation of the power supply. Only by clarifying the cause of the overheating of the transformer and dealing with the existing problems in a timely manner, can we reduce the failure caused by overheating and prevent the expansion of the fault.
I. Analysis of the causes of overheating of distribution transformers:
The overheating of the distribution transformer is different from that of normal operation. In normal operation, the temperature comes from the winding and the core. Overheating faults are mostly present in the solid insulation hot spots causing insulation degradation and pyrolysis. Hot spots often develop from low temperatures to high temperatures, and even rapidly develop as an arc causing the transformer to burn out. The hot spots are different, and the causes are mostly different.
Distribution transformer overheating faults mainly include:
1. Winding overheating After years of operation of the distribution transformer, it will cause insulation to expand, the oil passages between the winding sections will be blocked, the oil flow will be poor, and the insulation between the turns will not be protected by cooling. Under the long-term electromagnetic vibration, the aging insulation skin will fall off. , Forming a short circuit between turns or segments, causing the transformer to burn.
2. Tap-Changer The tap-changer will cause mechanical damage, electro-corrosion and contact contamination resulting in poor contact and loose joint overheating during long-term transformation.
3. Magnetic circuit faults The magnetic flux leakage of the silicon steel sheet causes local overheating. Iron core clamps and foreign bodies cause short circuit of the iron core or local circulation due to multiple points of the iron core to form a circulation.
4. Transformer leads As the lead breaks, the lead joints do not contact well, and the conductive rods loosen to form overheating.
5. Foreign objects are left inside the transformer during inspection or assembly. This may not only cause short circuits in the windings, but may also cause local overheating due to circulation in the foreign matter.
6, due to damage to the other cooling device, silica gel, silt blockage, oil blockage, etc. can cause transformer overheating.
Second, deal with measures:
The causes of local overheating of distribution transformers are different, and the treatment measures taken are different.
1. Due to overheating caused by internal components of the winding or transformer, it is necessary to look out of the box to see overheating, increase the insulation distance, make the oil flow unimpeded, handle the exposed wires, check the box body for no foreign matter, whether there is a grounding point and the parts to the shell The distance of the body should be appropriate while filtering the transformer oil to increase the dielectric strength.
2. When lead wires and tap-changers are used, lead wires and tap-changers should be properly connected, and the double screw caps fastened to the connection screws should be tightened to avoid heat generation due to loosening.
3, due to magnetic leakage caused by overheating failure, check, deal with leakage magnetic point (such as wear rod over the position, the folder touch the shell, etc.), all the components of the iron core fastening and insulation treatment, but also in the transformer tank inner wall The magnetic shield is installed so that the leakage flux passes through the magnetic shield with better magnetic permeability as much as possible, instead of penetrating into the steel plate of the tank wall to avoid large losses in the tank wall and causing local overheating of the tank.
4, due to cooler failure or overheating caused by blockage of the pipe, should replace the damaged fan, regular use of compressed air or water to clean the cooler tube.
5, to strengthen the daily inspection and monitoring of distribution transformers, observe the degree of discoloration of the silica gel transformer, oil level changes, timely replenishment in the absence of oil, use the "look, smell, ask, cut" method, or instrument inspection transformers, preventive Test, comprehensive judgment of the status of transformer operation.
I. Analysis of the causes of overheating of distribution transformers:
The overheating of the distribution transformer is different from that of normal operation. In normal operation, the temperature comes from the winding and the core. Overheating faults are mostly present in the solid insulation hot spots causing insulation degradation and pyrolysis. Hot spots often develop from low temperatures to high temperatures, and even rapidly develop as an arc causing the transformer to burn out. The hot spots are different, and the causes are mostly different.
Distribution transformer overheating faults mainly include:
1. Winding overheating After years of operation of the distribution transformer, it will cause insulation to expand, the oil passages between the winding sections will be blocked, the oil flow will be poor, and the insulation between the turns will not be protected by cooling. Under the long-term electromagnetic vibration, the aging insulation skin will fall off. , Forming a short circuit between turns or segments, causing the transformer to burn.
2. Tap-Changer The tap-changer will cause mechanical damage, electro-corrosion and contact contamination resulting in poor contact and loose joint overheating during long-term transformation.
3. Magnetic circuit faults The magnetic flux leakage of the silicon steel sheet causes local overheating. Iron core clamps and foreign bodies cause short circuit of the iron core or local circulation due to multiple points of the iron core to form a circulation.
4. Transformer leads As the lead breaks, the lead joints do not contact well, and the conductive rods loosen to form overheating.
5. Foreign objects are left inside the transformer during inspection or assembly. This may not only cause short circuits in the windings, but may also cause local overheating due to circulation in the foreign matter.
6, due to damage to the other cooling device, silica gel, silt blockage, oil blockage, etc. can cause transformer overheating.
Second, deal with measures:
The causes of local overheating of distribution transformers are different, and the treatment measures taken are different.
1. Due to overheating caused by internal components of the winding or transformer, it is necessary to look out of the box to see overheating, increase the insulation distance, make the oil flow unimpeded, handle the exposed wires, check the box body for no foreign matter, whether there is a grounding point and the parts to the shell The distance of the body should be appropriate while filtering the transformer oil to increase the dielectric strength.
2. When lead wires and tap-changers are used, lead wires and tap-changers should be properly connected, and the double screw caps fastened to the connection screws should be tightened to avoid heat generation due to loosening.
3, due to magnetic leakage caused by overheating failure, check, deal with leakage magnetic point (such as wear rod over the position, the folder touch the shell, etc.), all the components of the iron core fastening and insulation treatment, but also in the transformer tank inner wall The magnetic shield is installed so that the leakage flux passes through the magnetic shield with better magnetic permeability as much as possible, instead of penetrating into the steel plate of the tank wall to avoid large losses in the tank wall and causing local overheating of the tank.
4, due to cooler failure or overheating caused by blockage of the pipe, should replace the damaged fan, regular use of compressed air or water to clean the cooler tube.
5, to strengthen the daily inspection and monitoring of distribution transformers, observe the degree of discoloration of the silica gel transformer, oil level changes, timely replenishment in the absence of oil, use the "look, smell, ask, cut" method, or instrument inspection transformers, preventive Test, comprehensive judgment of the status of transformer operation.
Universal&Learning Romote Control
Shenzhen Chaoran Technology Corp. , https://www.chaoran-remote.com