Electric Motors: AC Versus DC
Posted on October 23, 2020
Michael Rodriguez
Electronics
Electric motors have a critical role in nearly all industries. Using the right motor in conjunction with high-quality parts and regular servicing ensures your machines will run smoothly and prevents equipment damage related to power surges. Electric motors are machines that convert electrical energy, whether from stored power or a direct electrical connection, into mechanical energy through the production of rotational force. There are two types of electric motors: AC motors, which are powered by alternating current, and DC motors, which are powered by direct current. This blog will explain the ins and outs of electric motors and their function.
AC and DC motors both use electrical current to produce rotating magnetic fields. Subsequently, these magnetic fields generate rotational mechanical force in the armature on the rotor or stator around the shaft. Though there are many differing motor designs, all use this same basic concept to convert electrical energy into pulses of force providing speed and power. Furthermore, nearly all electric motors contain the same basic parts and assemblies. These include a central motor shaft, widnings, bearings (to reduce friction and wear & tear), an armature (located on either the rotor or stator), brushes (which appear only in DC motors), terminals, and frame & end shields.
AC and DC motors are considered broad categories that comprise a number of smaller subcategories. For instance, induction motors, linear motors, synchronous motors, are all examples of AC motors. AC motors can also include variable-frequency motors which control the motor’s speed and torque. DC motors are available in self-excited (in which the current is provided by the motor itself) and separately-excited type models.
Both types of motors have different advantages that make them better suited to different commercial and industrial applications. For example, AC motors are lauded for their flexibility and ease of control. Other advantages of AC motors include:
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Low startup power demands that protect components on the receiving end
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Controllable starting current levels and acceleration
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VFD (variable frequency drive) or VSD (variable speed drive) additions that can control speed and torque at different stages of use
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High durability
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Long lifespans
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Capabilities for multi-phase configurations
DC motors also offer distinct advantages, including:
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Easier installation and maintenance
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High startup power and torque
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Fast response times to starting, stopping, acceleration, and deceleration
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Availability in a broad range of standard voltages
AC motors are usually thought of as more powerful than DC motors due to their ability to generate higher torque through the use of a more powerful current. Despite this, DC motors are more efficient and make better use of their input energy. To meet a wide array of requirements, both AC and DC motors are available in a variety of sizes and strengths.
For AC motors, the most common industrial uses include appliances, compressor drives & systems, computers, conveyor systems, fans &
air conditioners, hydraulic & irrigation pumps, and transportation equipment. DC motors, on the other hand, are used in fabrication & production units, warehouse sorting equipment, and any machinery that demands constant power, such as vacuums, elevators, and sewing machines. Selecting the right electric motor, as well as properly installing and maintaining it, is a critical step in ensuring smooth and efficient operation of your machine and your facility as a whole.