What is the working principle of an AC motor?
The operating principle of 120v ac motors is the same as that of the general squirrel-cage asynchronous motor, but the structure is different. It is made of a material with high resistivity (such as brass, constantan, etc.) as the guide bar and end ring of the rotor. . Therefore, the rotor resistance of the torque motor is much larger than that of a conventional squirrel cage motor. The mechanical characteristics of a torque motor are different from those of a conventional squirrel cage motor.
Due to the different design parameters, the mechanical characteristics and uses of the torque motor are divided into two categories: the torque motor with winding characteristics and the torque motor with constant torque characteristics. Winding characteristic torque motor for constant tension transmission, suitable for applications where the product needs to maintain a constant tension during production and wind the product on a roller at a constant line speed, for example, on a printing machine, winding the fabric The roller, as the fabric is continuously wound onto the roller, the diameter of the roller gradually increases and the load increases accordingly. It can be seen from the mechanical characteristics of the torque motor that the load increases and the rotational speed automatically drops, thereby maintaining a certain line speed and tension, and achieving the process requirements. Such torque motors are commonly used in textiles, printing and dyeing, paper, rubber, wire and cable.
Constant torque characteristic torque motor can make the torque basically constant in a wide range of speeds. It is suitable for transmission situations where constant torque is required when the two speeds change. For example, in a printing and dyeing machine, when a fabric is conveyed by a plurality of rollers, since the fabric is not wound on the roller shaft, but is simply attached to the surface of the roller shaft and driven by it, the diameter of the roller shaft is not changed. A constant torque characteristic motor is used to ensure that the torque is constant at any speed and the tension of the fabric is constant.
120v ac motors allows long-term low-speed operation (even blocking), and its heat is very serious. It is usually forced to air-cool by an external blower. When using the torque motor, please pay attention to check whether the operation of the blower is good, there should be a good ventilation environment around it, and dry and flammable materials are not allowed. Flammable dust or volatile fuels are close.
Due to different usage conditions, the type and specifications of materials wound or transmitted by the motor driven by the torque motor are different, the required tension is different, the torque of the torque motor is required to be adjusted, or the speed is required to be changed within a certain range, and the adjustment is usually applied to the torque. The voltage on the motor to achieve these requirements. Changing the input voltage of the torque motor usually uses a voltage regulator. In the case where it is required to improve the hardness and adjustment accuracy of the mechanical characteristics, the thyristor speed negative feedback control circuit can also be used for stepless speed regulation, but the system is complicated.
