A variable speed drive (VSD), also known as an adjustable speed drive (ASD), is used as an energy manager. By adjusting the amperage and voltage that is fed to the AC motor, the speed at which the motor runs can be adjusted; thus, its purpose is to determine the speed and torque of an AC motor.
An AC motor is powered by an alternating current and is an electric motor. The alternating current that it receives is transformed into mechanical power. It does this by making use of an electromagnetic induction phenomenon.
Variable speed drives for AC motors are available in electric, hydraulic, mechanical or electronic variations.
How Does an AC Variable Speed Drive Work?
An electric motor will always operate at a 100% capacity if it is not fitted with a variable speed drive. This means that other than when the motor is switched off, it will run at one constant speed and torque.
A variable speed drive makes use of printed circuit boards (PCB’s) to achieve speed and torque variation. The PCB’s control the power stage of the drive. The power stage is the input and output segment of a drive that the electrical current flows through. The size of the variable speed drive is determined by the size of the motor it needs to regulate, and the amount of electrical current it will be processing.
Applications of Variable Speed Drives
Variable speed drives are popular because they have a wide range of applications. From appliances to heavy machinery, VSD’s are present. Some of these applications include, but are not limited to:
- Elevators: In order for an elevator to gradually speed up and slow down, from and to a stop, the torque and speed of the motor that is powering that elevator needs to be controlled by a VSD.
- Cranes: Large cranes that lift and place containers require a VSD as they do change in speed and direction to successfully place their containers.
- Air Conditioners: These appliances do not operate at one speed, as more heating or cooling is required, the intensity needs to be adjusted.
An Economic Benefit
Variable speed drives do offer a few interesting benefits; however, there is one that makes the use of a VSD very appealing.
Not all machinery and appliances have to run at 100% capacity at all times. The capacity control that the VSD provides will result in the user saving energy. This makes a variable speed drive an economically beneficial device.
At EP Normand we stock a variety of variable speed drives and can assist you in choosing the correct drive for your required application. Contact us to find out more about variable speed drives and their applications.