AC motors are just one of the types of motors used in machinery both large and small and across multiple industries. While they do have their differences, all electrical motors have the same basic premise. Essentially, these motors use an electrical current to supply power to a motor, which sparks the other components to life. This usually starts with a rotating part of some sort.
In the case of an AC motor, the electrical current or voltage is produced via a changing electromagnetic field or induction. This induction process is used in many large factory machines as well as in units such as HVAC systems.
A Brief Look at AC Motors
The “AC” stands for alternating current, which helps to convert electrical energy into mechanical energy to power machines of different sizes. This alternating current flows through electric coils within the motor, creating an induction process and producing rotational energy. The power generated by this process is enough to support industrial-grade machines, which is why AC motors are often found in factory and automation settings.
AC motors are often compared to DC motors, and for good reason. They aren’t terribly different but they certainly aren’t the same. First of all, they have different power sources with DC motors having a direct power supply such as a battery and AC motors being powered by electromagnetic processes.
Another essential difference is speed control. DC motors have variable speed based on voltage changes while AC motors alter speed via frequency changes. Generally speaking, an AC motor is preferable for machines that require more fixed-speed procedures.
Frequency, Current, and Voltage
To dive a bit deeper into this, it’s good to look at the power requirements for an AC motor. They typically have a specified AC power rating to determine what they are best used for. A good example of this is frequency, which is measured in hertz (Hz). Lots of factories use AC motors with a frequency of 50 to 60 Hz although larger devices can go much higher than that.
Current, particularly starting current, is another indicator and is expressed in amps (A). When the AC motor starts, its initial current will be higher than its full output power, which is where it will stay overtime.
Finally, voltage is expressed as volts alternating current, or VAC. Large factory operations may have a VAC of around 460 to 600. If there is not enough voltage, the torque output will falter and slow down the motor. With too much voltage, the torque will ramp up and potentially damage the motor.
Selecting an AC Motor
When choosing an AC motor, it’s important to consider current, frequency, and voltage as well as things such as size and internal mechanisms. Each consumer will have different needs, which is why a large variety of AC motors is available on the market. It is also crucial to consider the working environment since things such as temperature and moisture can affect the motor’s efficiency. The good news is that many factories have established parameters for their chosen AC motors.
Benefits of AC Motors
AC or induction motors are available as self-starting devices, which can be especially convenient in a factory automation setting. Fortunately, as machine technology has advanced, the inner workings and controls of these types of motors have improved. For example, the speed and voltage controls for these motors can easily be altered via an AC drive, as can the synchronicity of the rotors.
Factory workers can even set the motor automation to match the operational requirements, decreasing the human margin of error. As time goes on, modern technology will bring even more benefits to these motors, such as easier operation and the capability to take on more challenging tasks.
One of the things to remember about large AC motors is that the initial surge of electrical current can be too much for the supply line, so these motors work best when they start at a lower voltage and slowly ramp up.
This is crucial for machine operators to remember, especially in a large factory setting, because cranking the voltage up high right away can cause the other devices in the area to experience a significant drop in power. It’s not uncommon to use an autotransformer to help with this variable-speed process.