How to deal with the heating of vacuum oil filter motor
2019/12/8??????view:
Principle of motor:
The basic principle of electric motor is electromagnetism. Electromagnetism is the use of a straight metal wire through the current, then the space around the wire will produce a circular magnetic field. The greater the current flowing through the conductor, the stronger the magnetic field produced. The magnetic field is round around the wire.
Motor is a kind of equipment that converts electric energy into mechanical energy. It uses the electrified coil (that is, the stator winding) to generate the rotating magnetic field and act on the rotor (such as the squirrel cage closed aluminum frame) to form the magnetoelectric rotating torque.
Motors are divided into DC motors and AC motors according to the different power supply. Most of the motors in the power system are AC motors, which can be synchronous or asynchronous motors (the motor stator magnetic field speed and rotor rotation speed do not maintain synchronous speed).
The motor is mainly composed of stator and rotor. The direction of force movement of electrified wire in the magnetic field is related to the direction of current and magnetic induction wire (magnetic field direction). The working principle of the motor is that the magnetic field acts on the current to make the motor rotate.
Causes of motor overload and heating:
The common cause of the motor heating of tya20 vacuum oil filter is very serious.
1. The air gap between the stator and rotor of the motor is very small, which is easy to cause the collision between the stator and rotor
In small and medium-sized motors, the air gap is generally 0.2mm-1.5mm. When the air gap is large, the excitation current is required to be large, so as to affect the power factor of the motor; if the air gap is too small, the rotor may have friction or collision. Generally, because the bearing is seriously out of tolerance and the inner hole of the end cover is worn and deformed, the frame, the end cover and the rotor are three different axes, which cause the bore cleaning, and it is easy to heat or even burn the motor. If it is found that the bearing is worn, it should be replaced in time, and the end cover should be replaced or brush plated. The simpler method is to insert a sleeve into the end cover.
2. The abnormal vibration or noise of the motor may easily cause the motor heating
This situation belongs to the vibration caused by the motor itself, most of which are caused by the bad dynamic balance of the rotor, the bad bearing, the bending of the shaft, the different axis of the end cover, the base and the rotor, the looseness of the fastener, the uneven foundation of the motor installation and the improper installation, or the transmission of the mechanical end, which should be excluded according to the specific situation.
3. If the bearing is not working normally, the motor will be heated
Whether the bearing works normally can be judged by hearing and temperature experience.
The bearing end can be tested by hand or thermometer to determine whether its temperature is within the normal range; the hearing bar (copper bar) can also be used to contact the bearing box. If the impact sound is heard, it means that one or several balls may be crushed. If the hissing sound is heard, it means that the lubricating oil of the bearing is insufficient, and the motor should be replaced with lubricating grease once around 3000-5000 hours of operation.
4. The power supply voltage is too high, the excitation current increases, and the motor will overheat
Too high voltage will endanger the insulation of the motor and make it have the danger of breakdown. When the power supply voltage is too low, the electromagnetic torque will be reduced. If the load torque is not reduced and the rotor speed is too low, the increase of the slip rate will cause the motor overload and heat, and the long-term overload will affect the life of the motor. When the three-phase voltage is asymmetric, that is, when the voltage of one phase is too high or too low, it will lead to excessive current of one phase and motor heating. At the same time, when the torque is reduced, it will make a "buzzing" sound, and the winding will be damaged if the time is long.
In a word, whether the voltage is too high, too low or the voltage is asymmetric, the current will increase and the motor will be heated and damaged. Therefore, according to the national standard, the change of the motor power supply voltage shall not exceed ± 5% of the rated value, and the motor output power can maintain the rated value. The power supply voltage of the motor shall not exceed ± 10% of the rated value, and the difference between the three-phase power supply voltage shall not exceed ± 5% of the rated value.
5. Winding short circuit, turn to turn short circuit, phase to phase short circuit and winding open circuit
After the insulation between two adjacent wires in the winding is damaged, the two conductors collide, which is called winding short circuit. The short circuit of winding in the same winding is called inter turn short circuit. The short circuit between two phase windings is called phase to phase short circuit. Either way, it will increase the current of a certain phase or two phases, cause local heating and damage the motor due to aging insulation. Winding open circuit refers to the fault caused by the stator or rotor winding breaking or burning. Whether the winding is short circuited or open circuited, the motor may be heated or even burnt. Therefore, the machine must be shut down immediately after this happens.
6. The leakage of materials into the motor reduces the insulation of the motor, thus reducing the allowable temperature rise of the motor
When solid materials or dust enter into the motor from the junction box, they will reach the air gap between the stator and rotor of the motor, causing the motor to sweep, until the winding insulation of the motor is worn out, causing the motor to be damaged or scrapped. If liquid and gas media leak into the motor, it will directly cause the motor insulation to drop and trip. Generally, liquid and gas leakage has the following forms:
Leakage of various containers and pipelines, sealing leakage of pump body, flushing equipment and ground;
After the mechanical oil leaks, it enters into the motor from the front bearing box gap;
The oil seal of the reducer connected with the motor is worn, and the mechanical lubricating oil enters along the motor shaft. After it accumulates in the motor, the insulating paint of the motor is dissolved, which gradually reduces the insulation performance of the motor.
7. Almost half of motor burnout is caused by motor phase loss operation
The lack of phase often causes the motor to be unable to run or the speed is slow after starting, or the current is too weak to rotate and there is a "buzzing" sound
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