Motors, also known as "motors," are machines that convert electrical energy into mechanical energy. The motor can be used to apply a large amount of electric energy generated by the generator to the production business. The construction is basically the same as the generator, but the principle is just the opposite. The motor is energized to the rotor coil to cause motion, while the generator generates current by the movement of the rotor in the magnetic field. In order to obtain a strong magnetic field, it is advisable to use an electromagnet regardless of the motor or the generator.
Motor structureThe structure of the three-phase asynchronous motor; the fixed part of the motor is called the stator, the stator is composed of the motor casing, three winding coils and silicon steel bars, and the rotor is the part that can be rotated by the motor. Mainly by the rotor silicon steel core is embedded with rotor coil, the bearing at both ends of the main shaft, the inner bearing of the bearing is the inner bearing cap of the bearing oil sump, the outer bearing cap of the outer bearing to prevent the bearing from moving, and the outer bearing cap of the bearing oil raft, the outer bearing cap edge is prevented The oil seal that the oil seeps out, and the motor blades at the end of the motor, the blades are also fixed with snap rings.
Professional motor maintenance and repair center motor maintenance process: cleaning the rotor - replace the carbon brush or other parts - vacuum class F pressure dipping paint - drying - school balance.
1. The use environment should be kept dry frequently, the surface of the motor should be kept clean, and the air inlet should not be hindered by dust or fibers.
2. When the thermal protection of the motor continuously occurs, it should be checked whether the fault is from the motor or the overload or the setting value of the protection device is too low, and the fault can be put into operation.
3. It should ensure good lubrication of the motor during operation. The general motor runs for about 5,000 hours, that is, the grease should be replenished or replaced. When the bearing is overheated or deteriorated during operation, the hydraulic pressure is changed in time. When replacing the grease, the old lubricating oil should be removed, and the oil groove of the bearing and the bearing cap should be cleaned by gasoline, and then the ZL-3 lithium base grease fills the cavity between the inner and outer rings of the bearing by 1/2 (for 2 poles). And 2/3 (for 4, 6, 8 poles).
4. When the end of the bearing life, the vibration and noise of the motor will increase significantly. When the radial clearance of the bearing reaches the following values, the bearing should be replaced.
5. When disassembling the motor, the rotor can be taken out from the extended end or the non-extended end. If it is not necessary to remove the fan, it is convenient to remove the rotor from the non-shaft extension. When the rotor is pulled out of the stator, damage to the stator winding or insulation should be prevented.
6. When replacing the winding, you must write down the form, size and number of turns of the original winding, wire gauge, etc. When the data is lost, you should obtain it from the manufacturer and change the original design winding at will, often making one or several properties of the motor. Deteriorated, even unable to use.
Motor check wiringWhether it is an AC motor or a DC motor, the windings are generally separated, and the windings are connected according to certain requirements and connected to the external circuit, which is called the wiring of the motor. The wiring of the motor is a very important task in the motor installation. Before wiring, you should understand the wiring diagram of the design drawing. When wiring, you can wire according to the wiring diagram in the motor junction box. The wiring methods vary.
The wiring of the DC motor is usually indicated on the cover of the junction box with a circuit diagram, which can be selected according to the excitation form and load steering requirements. Except that the dragged load has strict requirements on steering, the wiring of the AC motor will only reverse the motor without damaging the motor even if the phases are reversed. However, if the excitation winding and the armature winding of the DC motor are indirectly opposite each other, the motor armature may be charged, and the field winding may be de-energized without being charged, so that the motor may fly when it is no-load, and the rotor may be burnt when it is heavy. Therefore, the external wiring of the armature winding and the field winding of the DC motor must not be indirectly indirect with each other. External wiring of the motor. Before connecting the motor to the external wire, check whether the winding terminals of the end cap are loose. When the crimping screw of the internal lead wire is tightened, the shorting piece can be connected according to the required wiring method, and the external wire can be crimped. Before the motor is connected, check the insulation of the motor. It is best to complete the unit debugging of the motor before wiring. When the motor meets the requirements of the current specification, connect the external line. Generally, the insulation resistance of low-voltage motors is required to be greater than 0.5MΩ, and the shaking table is used at 500V. After the motor is installed and wired, the following checks should be carried out before the motor is commissioned:
(1) The civil engineering cleaning and finishing is completed;
(2) The motor is installed and the inspection is completed;
(3) The debugging of the secondary circuit such as the motor control circuit is completed and the work is normal;
(4) When moving the rotor of the motor, the rotation is flexible and there is no chucking phenomenon;
(5) All wiring of the main circuit of the motor is firmly fixed without any looseness;
(6) Other affiliated systems are fully qualified. Among the above six items, the installation electrician should pay special attention to the fifth article. The main circuit system described here refers to all the main circuit wirings from the power supply input of the power distribution cabinet to the motor terminal, and must be firmly connected. That is, each knife switch, air switch, contactor, fuse and thermal relay, the upper and lower contacts of the terminal block of the power distribution cabinet and the motor wiring must be firmly connected to ensure reliable and safe operation of the motor. Otherwise, there will be burning. The danger of a bad motor. When the motor is in trial operation, it is necessary to monitor whether the current of the motor exceeds the specified value and record it. In addition, the following items should also be checked:
(1) Whether the direction of rotation of the motor meets the requirements. When the AC motor is reversed, the two motors can be exchanged arbitrarily; when the DC motor is reversed, the two armature voltage wirings can be exchanged, and the two excitation voltage wirings can also be changed.
(2) The sound of the motor running meets the requirements, that is, there is no friction sound, screaming sound, card sound and other abnormal sounds, otherwise it should be stopped for inspection.
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