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Reasons for affecting the life of three-phase communication motors
Source: China Bearing Network Time: 2013-10-30
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The motor is in operation due to various reasons; it will present faults; the disease is divided into mechanical and electrical aspects.
1. There are problems such as brooms, oscillations, overheating of bearings, damage, etc.
1. The air gap between the stator and the rotor of the asynchronous motor is very high. The è€ è´¾ è´¾ Ä Ä 19 19 19 ( 通常 通常 通常 通常 通常 通常 通常 通常 è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾ è´¾The end cap and the rotor are not the same as the shaft to attract the broom. If it is found that the bearing should be replaced in time; replace the end cap or brush plating.
2, the oscillation should be distinguished by the motor itself; it is still caused by the poor transmission; perhaps it is transmitted from the mechanical load end; then it is scanned according to the specific situation. It is attributed to the oscillation caused by the motor itself; most of it is due to the rotor movement The balance is not good; and the bearing is bad; the shaft is twisted; or the end cover, the base, and the rotor are not the same; the foundation of the motor device is not flat; the device is not in place; the fastener is loose, the oscillation will be noisy; load.
3. If the bearing operation is not normal; it can be judged by the experience of hearing and temperature. Touch the bearing box with the listening rod (copper rod); if the impact sound is heard; it means that there may be one or several balls broken; if it is heard There is a buzzing sound; that is to show that the lubricating oil of the bearing is lacking; because the motor needs to change the grease once every 3000-5000 hours of operation, for example, the ball mill motor in our sub-factory section is JR138--8245KW; More than a year later; the bearing announced abnormal movements; touched the bearing box with the listening stick; heard the movement of "å’å’"; together with the impact of a small "å“’å“’"; is catching up with the factory to stop production for maintenance; Turning over and finding that there is no oil in the bearing box; some bearing rollers have slender hemp marks. This replaces the bearing; adding grease. Not too much when adding grease; if too much, the bearing will rotate somewhat It has a large friction and heat between the grease and the grease; usually the grease placed in the bearing box is about one-half to two-thirds of the total dissolved. If it is not correct in the bearing device; Tight or too loose; also Will cause the bearing to heat. In the horizontal motor, the outstanding bearing is only subject to radial stress; if the cooperation is too large, the bearing will be over the bearing. The 惺 å’诹悖 å’诹悖 å’诹悖 å’诹悖 å’诹悖 涣榛 涣榛 涣榛 涣榛 涣榛 涣榛Core protrusion (4).
Second, electrical aspects of the voltage is not normal winding grounding winding short-circuit winding open circuit phase loss operation.
1. The power supply voltage is too high; the excitation current is increased; the electric timing is overheated; the high voltage of the overheating may endanger the insulation of the motor; the risk of being broken down. When the power supply voltage is too low; the electromagnetic torque will be greatly reduced; If the load torque is not reduced, the young stop is awkward, and the test is awkward. (4) 龋怀ãªå¥”æµ åµŠè·‹æ–“ç¼æ°–倜. When the three-phase voltage is asymmetrical; that is, the voltage of one phase is high or low. The current will be too large; the motor will heat up; the reduction of the torque will announce the sound of "Weng Biao"; the long time will damage the winding. The total current will be added regardless of the voltage is too high or the three-phase voltage is asymmetrical; The motor generates heat and damages the motor. Therefore, according to the national standard, the motor power supply voltage is changed within ±5% of the rated value; the motor output power is up to the rated value. The motor power supply voltage is not allowed to exceed ±10% of the rated value; The difference should not be greater than ±5% of the rated value.
2, the winding insulation of the motor is damaged; and the conductor of the winding and the core and the casing are connected to each other, that is, the winding is grounded. At this time, the current of the phase winding is too large; some are heated; the winding is burned when it is severe. Most of them are caused by moisture in the motor; some are made up of metal or harmful powder entering the motor winding when the environment is bad. The motor is grounded after the winding is grounded; except that the insulation is aging, dry, and brittle, there are some treatments; the winding grounding usually occurs in the winding extension. The junction outside the slot (winding end); at this time, it can be penetrated between the core and the winding with natural mica or insulating paper at the fault; dry it with insulating tape and apply it with insulating paint; if it is connected If the location is in the iron core slot; if the insulation is damaged on the upper edge; the groove can be repaired by the groove wedge or the upper wire can be lifted for disposal; if the fault is damaged at the bottom of the groove or in many places; the best way is to replace the winding.
3. After the insulation between two adjacent wires in the winding is damaged; the two conductors collide; it is called the winding short circuit. The winding short circuit in the same winding is called the inter-turn short circuit. The attack occurs between the two-phase windings. Winding short circuit is called phase-to-phase short circuit. No matter which one; it will cause a phase or two-phase current to be added; it will cause some heat; make the insulation aging damage the motor. When the winding is short-circuited; it is not difficult to repair the short-circuit point outside the slot. Attack in the groove; if the coil is not damaged seriously; the coil coil can be heated and softened and then turned out to be damaged; replaced with new slot insulation; the damaged part of the coil is wrapped with a thin insulating tape and coated with insulation The paint is dried; it is viewed with a multimeter; the proof has been repaired; it is embedded in the groove from the beginning; it can be used continuously after insulation treatment; if the coil is damaged too much; perhaps the coil side after the new insulation can not be embedded ; had to replace the new winding.
4. Winding open circuit refers to the fault that the stator or rotor winding of the motor is broken or blown. The stator winding is broken; the joints of the winding components and the lead wires are adjacent. These parts are exposed on the outer surface of the motor housing and the wires are simply broken. The joints will also be loose after long-term use due to improper welding; they will be connected from the beginning after being found; they can be used after being wrapped and coated with insulating paint. For example, the type of recovery crane of our factory is Y132M-47. 5KW was arrested after the operation was announced. After the inspection, it was found that the winding was disconnected. After opening the motor cover, it was found that the outer conductor of the motor casing was disconnected from the winding; the reason was that the welding was not true; Untie the rope; turn it off after welding; apply it after applying the insulating varnish. If the winding composed of faults is blown, replace the winding. If the rotor winding breaks, it can be judged according to the motor transition. Usually, the speed is slow; the transition is weak; the three-phase current of the stator is increased and there is a "å—¡å—¡" appearance; sometimes it cannot be started. When the rotor winding is broken, the rotor is first taken out to find the open circuit. Usually; it is usually caused by the cracking of the slip ring and the rotor coil; it can be used after welding from the head. If it is inside the coil, special equipment such as broken strip detector is usually used to determine the breaking part. For example: I am working in the factory. Car trolley motor type JZR212-63. 5KW when driving; suddenly found the car is weak; and accompanied by the sound of Weng Weng. After the inspection found that the rotor is one-phase open. Open the rotor and see the slip ring and the rotor coil junction welding; Dispose of the joint with gauze; clean it with a soldering iron; use it after welding.
5, three-phase special motor in the operation process; breaking a front or breaking a phase winding will constitute a phase loss operation (commonly known as single phase); if the load on the shaft is not changed; then the motor is in a severe overload condition; the stator current will Reaching the rated value twice or even higher; the motor will burn out at a slightly longer time. In all industries; the motor that burns due to lack of phase operation accounts for the largest proportion. Usually the motor phase loss is due to the melt touch of a phase fuse. Bad; or the fuse is too tight and simply broken; or the melt current has been selected. 庋ü oyster source 缶 鄱 鄱 鄱 鄱 挥 挥 挥 挥 挥 ( ( ( ( ( ( ( ( ( ( The rifle is evenly smashed. Sometimes the motor load line is broken; it is usually a broken wire caused by improper installation; especially the small ring kinks that occur when the single-core wire is released; the joint damage may cause the wire to be in operation. Sudden disconnection. Due to the long-term use of the motor, the internal joints or leads of the winding are loose or some overheating causes the winding to blow the motor out of phase loss operation. Totally no matter what kind of phase loss; only need to be found in time; Will constitute In order to prevent damage to the motor presents phase operation; In addition to the correct selection and low-voltage electrical equipment; should strictly implement the relevant standards; laying feeder lines; strengthen together regularly to look for and protection.
6, the grounding device of the motor. Motor grounding is an important link; however, some units often ignore this point; because the motor is not clearly grounded can also work; but this gives the production and personal safety buried an unsafe risk. Because of insulation once After the damage, the outer casing will have a risk of ground voltage; this will directly affect the safety of the person and the stability of the equipment. Therefore, the motor must have a safety ground. The so-called motor grounding is to pass some metal that is not charged under normal conditions. The grounding device is electrically connected to the earth; the grounding of the motor is the grounding of the metal casing. Thus, even if the device is grounded and short-circuited, the current will be semi-spherically dispersed through the ground to the earth; the current will form a voltage drop when it flows into the earth. This ensures equipment and personal safety.
Third, the conclusion is summarized; in order to be able to use the correct method to repair the fault of the motor; it is necessary to understand the characteristics and causes of the common faults of the motor; to do less detours; save time; remove the problem as soon as possible; rehabilitation motor problems; Make the motor in normal working condition. Do a good job of timing and protection of the motor; it is also one of the useful ways to ensure the safe operation of the motor;
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