Commercial and industrial power systems can get quite complex — sometimes it feels like you need an engineering degree to begin to understand the various components. But taking the time to learn about different parts of an enterprise-grade electrical system can pay off big time in terms of performance and efficiency. An organization can easily optimize operations and meet energy goals with the right equipment in place.
It’s useful for everyone involved in decision-making and facility budgeting to gain a working understanding of the electrical equipment within a facility, and how to choose the best parts for the job. An example of a component worth evaluating is a variable speed drive (VSD), sometimes also called a variable frequency drive (VFD).
Here are six factors to consider when choosing variable speed drives for commercial and industrial applications.
Variable Speed Drives: Functionality and Importance
To better understand the selection criteria for purchasing these components, let’s discuss the purpose variable speed drives serve within an electrical system.
Put simply, VSDs help control motor speed. It’s inefficient to have motors maxing out regardless of the actual amount of power needed by a certain process at a certain time.
According to Energy Management in Plastics Processing by Robin Kent, VSDs convert a fixed-frequency AC supply to a variable-frequency AC supply. This “controls the power use and mechanical power output so that the motor can run at the most efficient speed for the motor and the process.” For instance, VSDs could receive feedback from the process about temperature or pressure and adjust the power supply to the motor accordingly.
VSDs can also help reduce torque to protect machinery from damage that can occur with a rough start, which helps lengthen the lifespan of devices with motors.
Even minor adjustments to the speed of motors, pumps, conveyers and fans can reduce energy consumption greatly — not to mention wear and tear on equipment. This is how VSDs have the power to directly optimize operating costs and environmental impact for an enterprise.
Now let’s take a closer look at some factors to consider when you’re picking out variable speed drives for commercial and industrial utilization.
Factors to Consider When Choosing a VSD
As Processing Magazine notes, it’s not necessarily enough to match a VSD’s horsepower rating to the motor it will be controlling.
Other factors you’ll need to consider include:
- Operating profile of the load it controls: Will the VSD be controlling constant or variable loads? Will it be controlling a motor with frequent starts and stops or will the operation be continuous?
- Peak torque demand: Determine the most torque the motor will ever demand to ensure the VSD you choose can provide enough.
- Highest peak current at any time: Determine the most current the motor will ever demand to choose a VSD capable of providing the necessary power.
- Overload: How much overload can a given VSD handle and for how many seconds? This is important for situations demanding extra torque and current.
- Interface to the VSD: How will you be controlling your VSD? Using a programmable logic controller (PLC) facilitates digital communication with the VSD as opposed to hardwired discrete or analog I/O inputs. Choosing a VSD capable of interfacing with a PLC system also allows for more immediate monitoring of the drive’s performance.
- Harmonics: VSDs can emit harmonics, or distorted current and voltage waves, which means organizations will need a way to filter these out to reduce strain on equipment.
Getting familiar with the different options and parameters for various VSDs will help you choose parts most compatible with your systems and amenable to your needs.