What are the special requirements for explosion-proof motors during maintenance?

1. Explosion proof motors shall not be disassembled at will; During disassembly and maintenance, the explosion-proof surface of the component cannot be used as a fulcrum for the pry bar, and it is not allowed to strike or impact the explosion-proof surface. 2. When disassembling the motor, the fan cover and fan should be removed first, and then the bolts of the end cover and bearing cover should be disassembled with a sleeve wrench. Then, a round wood or copper rod should be used to impact the shaft extension along the axial direction to separate the end cover and the machine base, and finally the rotor should be removed. Dismantle the parts, place the explosion-proof surface facing upwards, and cover it with rubber or cloth pads. Be careful not to lose the fastening bolts, spring pads, etc. 3. When dipping and assembling, the insulation paint or dirt attached to the explosion-proof surface should be cleaned thoroughly. Hard objects such as iron sheets should not be used to scratch, but uneven areas can be ground with oilstone. 4. If the explosion-proof surface is damaged, lead tin solder HISnPb58-2 must be used, with a flux of 30% concentrated hydrochloric acid (for steel parts) or tin zinc solder containing 58-60% tin. The flux should be ammonium chloride 30%, zinc chloride 70%, and a mixed solution of water 100-150% (for cast iron parts) for welding repair. The bonding between the solder and the part should be firm, and the protruding part should be ground flat to achieve the specified smoothness. 5. To prevent rust on the explosion-proof surface, oil or 204-1 displacement rust proof oil should be applied on the explosion-proof surface, but paint is not allowed.

30

2024

/

01

What is the working principle of a three-phase asynchronous motor?

(1) Generation of rotor induced current When the stator winding of an electric motor is supplied with three-phase symmetrical alternating current, a rotating magnetic field rotating at a speed of ns is generated between the stator and rotor. Since the rotor is initially stationary, the rotor conductor will be cut by the rotating magnetic field. According to the principle of relative motion, we can also consider the magnetic field as stationary, while the rotor conductor rotates relative to the magnetic field, cutting the magnetic field lines and generating induced electromotive force. As the two ends of the rotor conductor have been short circuited by a short-circuit ring, the conductor has formed a closed circuit, so induced current is also generated in the rotor conductor. (2) Generation of rotor electromagnetic torque The rotor conductor that generates induced current is called an electrified conductor. The electrified conductor is subjected to electromagnetic force in a magnetic field, generating electromagnetic torque to drive the rotor to rotate. Moreover, we can also determine the direction of rotation of the rotor conductor based on the left-hand rule, which is the same as the direction of the rotating magnetic field, but operates at a speed slightly lower than the rotational speed of the rotating magnetic field. Due to the fact that the speed n of this type of motor is always lower than the speed ns of the rotating magnetic field, it is called an asynchronous motor. Also, because the rotor current of this type of motor is generated by electromagnetic induction, it is also called an induction motor.

10

2024

/

01

< 12345 > proceed page OK