What is the difference between constant torque and constant power?
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Help, as the title says. It would be best to have a simple explanation, such as whether the water pump operates at constant power or constant torque What about plastic extruders? Explain the principle?
The difference between constant torque and constant power lies in the fact that, in AC variable-frequency speed control systems, when the frequency is reduced below the base frequency of 50Hz, the motor can maintain constant torque; whereas when the frequency is above the base frequency, the motor can only maintain constant power, with the torque decreasing as the speed increases. As for the operating conditions of water pumps and other equipment, it depends on the frequency range in which they operate.
In the operation of any machine, there are forces or torques that oppose motion, commonly referred to as resistance or opposing torque. The mechanical characteristics of a load refer to the relationship between the braking torque and speed. The characteristic of a constant torque load is that the magnitude of the load torque depends only on the weight of the load, and not on the speed of rotation. Its power is proportional to the speed. Typical equipment includes belt conveyors. Characteristics of a constant-power load: The power remains essentially unchanged as the speed changes; it should not be confused with the weight of the load. Since winding machinery is a typical constant-power load, when the material of the object being wound differs, the required tension and linear speed also change, and consequently the winding power varies as well. The magnitude of the load torque is inversely proportional to speed. Centrifugal fans and pumps are typical square-law loads. Its load torque is proportional to the square of the speed, and its power is proportional to the cube of the speed.