Generally, there are three types of motors - an AC motor, a DC motor, or a servo/stepper motor. The motor you choose is dependent on your specific industrial application and its individual, special requirements. For example, a DC motor, whether brush or brushless, is often used in automobiles, while a stepper motor is utilized in process control systems. Each is suited for different, varying tasks.
Industrial automation motor load types are the next critical aspect to consider when evaluating your company’s needs. They can be divided into four major categories:
Variable horsepower and constant torque (1) applications include cranes, conveyors, and gear-type pumps. The torque remains constant because the load does not change. Because of the varying degrees of horsepower required to operate these types of machines, a constant speed AC or DC motor are good options to consider.
A variable torque and constant horsepower (2) load type is useful for machines in which speed remains constant and the load changes. A prominent example is a machine that rewinds paper. With this load type, it is important to consider regenerative power when sizing the motor or selecting the energy control method. For a large system, an AC motor with encoders, closed-loop control, and full quadrant drives may be beneficial, while a DC or servo motor can be a good application for a small system.
Variable horsepower and torque (3) load types are primarily found in applications such as fans, centrifugal pumps, and agitators. In these applications, horsepower and torque work in tandem. As a motor’s speed increases, the load output increases causing an increase in required horsepower and torque.
Finally, positional or torque control (4) is utilized in precise applications such as a linear actuator. While servo or stepper motors are often the best options for these applications, an AC motor with an encoder or DC motor with feedback can be used for tight torque control as well.
Application types are another important aspect to consider when selecting an industrial engine. The three main applications for industrial motors are constant speed, variable speed, and position (or torque) control. These applications control the rate at which the industrial motor runs and varies dependent on the type of machine. It is important to note that all motor types - AC, DC, and servo/stepper - can operate on any application. Selecting the correct application type falls on the consumer. Does your machine require frequent accelerations and decelerations? Then the constant speed application is not for you and you should look into the variable speed application.
With the complexities surrounding the subject, it is critical to do your due diligence before making any major decision regarding the purchase of your industrial motor. There are a myriad of factors to consider - motor type, motor load type, application type - and all must be carefully considered. Be sure to take your time and ensure that you are picking out the right motor for your company’s needs.
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