AC Drives

An AC drive is a device that is used to control the speed of an electric motor. There are different types of AC drives that are designed for specific applications and these are found in a range of settings, including industrial and commercial, as well as automation.

At RS, we stock hundreds of AC drives, so you’re sure to find the one to suit the job you’re working on. Whether you need a micro AC drive or a tech drive, you’ll find that we have a full selection in stock.

Read on to find out more about AC drives.

What are AC drives?

An AC drive is a device that converts a fixed frequency and voltage to an adjustable frequency and AC voltage source, controlling the speed, horsepower, and direction of an AC electric motor. They do this by converting the AC supply to DC using a converter (also known as a rectifier), and then inverting it back from DC to AC using the inverter to run the motors. To sustain the proper power factor and reduce the risk of excessive heating of the motor, the name plate volts/ hertz ratio must be maintained, and this is the main task of the AC drive.

The AC drive comprises three main components:

• The AC motor: This drives the device it’s being applied to, for example a fan or pump
• The motor control section: Often referred to as the inverter section, this controls the speed of the motor by converting utility power into adjustable frequency power
• The operator interface: The system that allows the operator to use controls to command the motor to function

What are the different types of AC drives?

The different types of AC drives are defined by the type of AC motor being used. There are several of these that you may come across, however the most common types are induction, synchronous, sensorless vector, and servo motors.

The current in induction motors is generated onto the rotor windings. Inductor motors are able to provide significant power levels and variable speed limits, making them a suitable choice for different applications. Synchronous motors work at a constant speed and the rotor speed is equal to the speed of the magnetic field of the stator. These are used where an exact speed must be maintained.

Sensorless vector motors have independent control of the voltage and frequency supplied to the motor, offering good speed control. Servo motors, meanwhile, are magnetic synchronous motors that can offer high acceleration ratings.

Where are AC motor drives used?

There are different applications for AC drives. They are especially suited to applications where precise speeds are required.

Some of the main reasons to introduce an AC tech drive include enhancing controls of your systems that use electric motors to operate, reducing energy usage and generating energy efficiently, and reducing the amount of pressure and stress on motor control applications in order to prolong their lifespan and reduce the need to replace parts.

AC drives are found in a range of industries and sectors, including power generation, mining, oil and gas, as well as the food and beverage industry.

In industrial applications, AC motor drives have been introduced to control medium voltage motors. In many cases, they have replaced traditional mechanisms and systems in order to reduce costs and waste. For example, in mining, long conveyors powered by slip ring motors have been used for decades. However, these cost more to run than AC drives and are less energy efficient, so the industry is making the switch.

Why choose RS for AC drives?

We stock a full range of AC drives that are designed to control electric motor speeds efficiently and effectively. We are a leading authorized distributor of AC drives in North America and stock leading names, including Schneider, ABB, and Siemens AC drives, so you’re assured of quality products. Additionally, each of these devices meet the highest industry and safety standards.

If you have any questions, our team is here to help. Contact us for advice and tips. You can also find more information in our expert content hub.