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Key points of quality control in high-voltage motor manufact
source：未知 time：2024-09-13 10:36nbsp; click：
The motor is a relatively simple machine. When the stator and rotor are put together and the two end covers are buckled, it is a complete motor. However, such a simple machine integrates electromechanical energy conversion and the essence of many disciplines, so it is not easy to design a perfect motor. Any small defect or negligence may lead to catastrophic consequences.
Generally speaking, the motor consists of two parts: electrical and mechanical. The key technology of the electrical part is insulation, and the mechanical part involves transmission theory and fluid mechanics. In addition, in the process of realizing energy conversion and transmission functions, various forms of loss are manifested in the form of heat, so naturally the problems of heat transfer and heat exchange cannot be ignored. Therefore, it is not an easy task to make a good motor, and it is even more difficult to make a high-voltage motor. Ms. Shen will not talk about topics involving too much theoretical analysis today, but will talk about common problems of motors and the measures that should be taken.
In addition to the welding problems encountered by my friend Lao G, occasional faults such as slot wedge falling off, various abnormal vibrations and noises caused by bearing system problems, insulation treatment defects, high temperature rise, etc., also occur frequently, and they are not repeated, making it difficult to guard against. Such problems are often more sensitive and have more serious consequences when they occur in high-voltage motors.
Welding problems and avoidance measures The connection between the poles of the motor winding, the winding main line and the lead, and the lead and the joint are the links where welding problems frequently occur. Problems such as cold welding and incomplete welding during the processing process often lead to desoldering during the operation of the motor, resulting in increased resistance at the welding site and severe local heating that causes the welding position to be disconnected. This problem mostly occurs at the welding position of the rotor parallel head cover of the winding motor, the stator and rotor lead and the main line. The winding rotor motor often has many rotor star point parallel heads, which are also the frequent points of cold welding or incomplete welding defects. To solve this type of problem, efforts should be made to improve the process: ● Use equipment and processes with high reliability. For example, most motor manufacturers use relatively reliable methods such as medium frequency welding, argon arc welding, and cold-pressed joints to assist silver-copper solder filling.
● Improvement of stator binding. After wiring, the welding position should be bound and solidified. It is strictly forbidden to leave the welding point in the air to prevent the vibration during the operation of the motor from causing the welding point to open due to stress. ● Use a rotor bracket to ensure that the end of the winding rotor winding is supported to prevent radial stress from opening. ● Pay special attention to the welding point where the lead wire is connected to the main wire, and try not to choose thin electromagnetic wire, that is, avoid the situation where the length and width of the flat wire section are greatly different.
The problem of slot wedge falling off and its preventive measures During the manufacturing process of high-voltage motors, some motor manufacturers use the immersion process. If the stator core coil slot full rate is low, the curing effect of the winding cannot be guaranteed during the varnish dipping process. When the motor is running, the coil will vibrate in the core slot due to the electromagnetic force, causing the slot wedge to fall off due to vibration, thereby causing problems such as bore sweeping and winding heating and burning.
At present, many domestic motor manufacturers use magnetic slot wedges. Although the motor efficiency performance is improved significantly, the slot wedge falling problem is more prominent. To solve this problem, the following aspects should be controlled: ● Control the matching relationship between the stator slot and the slot wedge, and the matching between the two should not be too loose; ● The slot filling rate should not be too low when embedding the wire. If this problem exists, the filling effect should be ensured by adding necessary insulating materials and improving the varnishing effect. Such as using vacuum varnishing process, controlling the viscosity of the varnish, secondary varnishing and other specific measures.
Bearing system problems and countermeasures Because the maintenance of sliding bearing motors is relatively troublesome, most high-voltage motors use rolling bearing structures. In the design of high-voltage motors, C3 clearance bearings are generally selected, and some extra-large motors use C4 clearance. This design change has brought new problems: many customers found that some ball bearings have point-like abrasion on the inner ring surface and cylindrical bearings have stripe-like abrasion when they use and repair motors. The reason is caused by the rotor shaft current. When the shaft current passes through the bearing, the roller path is irregularly connected and disconnected, generating electric sparks to burn the rollers and raceways, forming point-like pits, causing bearing vibration and increased wear. In severe cases, the bearing falls apart, the stator and rotor rub and heat up, and the motor burns.
Experienced customers install a carbon brush on the motor rotor coupling, and fix the brush holder on the motor end cover to directly ground the shaft current across the bearing, reducing or avoiding the occurrence of such failures. Some motor manufacturers use insulating bearings or insulating bearing sleeves to block the path of shaft current passing through the bearing.
Directly related to the bearings is the grease problem. The selection of grease must match the motor and the operating conditions. It is strictly forbidden to use inferior grease to prevent bearing problems caused by it.
low voltage electric motor, Ex motor, Motor manufacturers in China, three phase induction motor, Wolong Nanyang Explosion Protection
Generally speaking, the motor consists of two parts: electrical and mechanical. The key technology of the electrical part is insulation, and the mechanical part involves transmission theory and fluid mechanics. In addition, in the process of realizing energy conversion and transmission functions, various forms of loss are manifested in the form of heat, so naturally the problems of heat transfer and heat exchange cannot be ignored. Therefore, it is not an easy task to make a good motor, and it is even more difficult to make a high-voltage motor. Ms. Shen will not talk about topics involving too much theoretical analysis today, but will talk about common problems of motors and the measures that should be taken.
Welding problems and avoidance measures The connection between the poles of the motor winding, the winding main line and the lead, and the lead and the joint are the links where welding problems frequently occur. Problems such as cold welding and incomplete welding during the processing process often lead to desoldering during the operation of the motor, resulting in increased resistance at the welding site and severe local heating that causes the welding position to be disconnected. This problem mostly occurs at the welding position of the rotor parallel head cover of the winding motor, the stator and rotor lead and the main line. The winding rotor motor often has many rotor star point parallel heads, which are also the frequent points of cold welding or incomplete welding defects. To solve this type of problem, efforts should be made to improve the process: ● Use equipment and processes with high reliability. For example, most motor manufacturers use relatively reliable methods such as medium frequency welding, argon arc welding, and cold-pressed joints to assist silver-copper solder filling.
● Improvement of stator binding. After wiring, the welding position should be bound and solidified. It is strictly forbidden to leave the welding point in the air to prevent the vibration during the operation of the motor from causing the welding point to open due to stress. ● Use a rotor bracket to ensure that the end of the winding rotor winding is supported to prevent radial stress from opening. ● Pay special attention to the welding point where the lead wire is connected to the main wire, and try not to choose thin electromagnetic wire, that is, avoid the situation where the length and width of the flat wire section are greatly different.
The problem of slot wedge falling off and its preventive measures During the manufacturing process of high-voltage motors, some motor manufacturers use the immersion process. If the stator core coil slot full rate is low, the curing effect of the winding cannot be guaranteed during the varnish dipping process. When the motor is running, the coil will vibrate in the core slot due to the electromagnetic force, causing the slot wedge to fall off due to vibration, thereby causing problems such as bore sweeping and winding heating and burning.
At present, many domestic motor manufacturers use magnetic slot wedges. Although the motor efficiency performance is improved significantly, the slot wedge falling problem is more prominent. To solve this problem, the following aspects should be controlled: ● Control the matching relationship between the stator slot and the slot wedge, and the matching between the two should not be too loose; ● The slot filling rate should not be too low when embedding the wire. If this problem exists, the filling effect should be ensured by adding necessary insulating materials and improving the varnishing effect. Such as using vacuum varnishing process, controlling the viscosity of the varnish, secondary varnishing and other specific measures.
Bearing system problems and countermeasures Because the maintenance of sliding bearing motors is relatively troublesome, most high-voltage motors use rolling bearing structures. In the design of high-voltage motors, C3 clearance bearings are generally selected, and some extra-large motors use C4 clearance. This design change has brought new problems: many customers found that some ball bearings have point-like abrasion on the inner ring surface and cylindrical bearings have stripe-like abrasion when they use and repair motors. The reason is caused by the rotor shaft current. When the shaft current passes through the bearing, the roller path is irregularly connected and disconnected, generating electric sparks to burn the rollers and raceways, forming point-like pits, causing bearing vibration and increased wear. In severe cases, the bearing falls apart, the stator and rotor rub and heat up, and the motor burns.
Experienced customers install a carbon brush on the motor rotor coupling, and fix the brush holder on the motor end cover to directly ground the shaft current across the bearing, reducing or avoiding the occurrence of such failures. Some motor manufacturers use insulating bearings or insulating bearing sleeves to block the path of shaft current passing through the bearing.
Directly related to the bearings is the grease problem. The selection of grease must match the motor and the operating conditions. It is strictly forbidden to use inferior grease to prevent bearing problems caused by it.
Temperature rise and motor cooling Large high-voltage motors are designed with cooling devices. Currently, air-to-air cooling cabinets and water-cooling cabinets are commonly used. In addition to temperature rise control in product design, the following issues should be noted during use: ● The cooler must be in working condition when the motor is running.
● The rotation direction of the air cooler motor must comply with regulations.
● The water quality of the water cooler must meet the requirements.
Rotor insulation treatment problems There are many insulation faults on the rotor, collector ring and lead of high-voltage winding motors. Common fault cases include: the rotor lead is not firmly fixed, causing the insulation wrapping to loosen, and the insulation material wears during the rotation of the rotor, causing a short circuit to the ground; the isolation insulation sleeve between the three phases of the collector ring is loose and worn, causing a phase-to-phase short circuit; the rotor lead is pulled due to centrifugal force, causing the lead to be disconnected from the star point, etc.
Rotor insulation treatment problems There are many insulation faults on the rotor, collector ring and lead of high-voltage winding motors. Common fault cases include: the rotor lead is not firmly fixed, causing the insulation wrapping to loosen, and the insulation material wears during the rotation of the rotor, causing a short circuit to the ground; the isolation insulation sleeve between the three phases of the collector ring is loose and worn, causing a phase-to-phase short circuit; the rotor lead is pulled due to centrifugal force, causing the lead to be disconnected from the star point, etc.
low voltage electric motor, Ex motor, Motor manufacturers in China, three phase induction motor, Wolong Nanyang Explosion Protection
上一篇：Factors causing overheating and burning of motor windings | 下一篇：What is the impact of heat dissipation medium on temperature
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