As your facility continues to evolve and upgrade to meet modern standards, selecting the right equipment becomes increasingly important.
With a wide variety of options available, it’s essential to choose the most suitable solution for each specific application. One key consideration in this process is deciding between soft starters and VFDs (variable frequency drives). Each serves a unique purpose and fits different needs; there is no right or wrong choice, just the right choice for you.
At HESCO, we strive to provide our customers with guidance that leads to decisions that benefit their facilities, not financial burdens with no end in sight. If you’re trying to understand the difference between soft starters and drives, check out the article below. By the end, you’ll know which one would best suit your needs.
What is a Soft Starter?
A soft starter is a device designed for the controlled starting and stopping of a motor. As the motor starts up, the soft starter gradually increases the voltage for a smooth acceleration. This ultimately reduces the mechanical stress on the motor, preventing potential damage caused by any sudden rushes of power.
Features of a Soft Starter
The design of a soft starter makes it perfect for specific instances where you’re looking to have a motor start and stop smoothly or looking to reduce wear and tear.
Soft starters offer flexible programming options, allowing you to set the cadence of starting and stopping, according to your facility’s needs. This can be accomplished with a HIM (human interface module) or with the use of Dip Switches. These starters come with LED display features that provide clear visibility of the run status. Additionally, they are rated for multiple voltages and environments, enabling them to withstand a multitude of voltages a motor may have, regardless of the environment.
More technical features include:
- Fieldbus connectivity: Fieldbus is a collection of industrial computer networks and protocols that allows communication between industrial field equipment. With Fieldbus connectivity, the soft starter does not need to connect directly back to the controller, eliminating the need for additional output devices.
- Modular auxiliary contact capability: this allows the soft starter to indicate contact status. Ultimately, this feature is used for remote visual signaling and alarming, ensuring you receive a notification without the need to be physically near the soft starter and motor if something were to go wrong, such as the motor failing or being interrupted.
What is a Variable Frequency Drive?
A variable frequency drive (VFD) is a device that starts a motor with the capability to control how fast the motor is moving, while simultaneously controlling the torque that motor outputs. While soft starters simply give the motor a smooth start and stop, VFDs can control and vary the speed throughout the operation.
Features of a VFD
Similar to a soft starter’s programming, VFDs have multiple control modes and parameter settings, allowing you to control the cadence of how the drive is operating in the motor. Since the drive runs throughout full operation, there are more parameter settings in which you can control the speed and torque of the motor. Additionally, they are rated for multiple voltages and environments, enabling them to withstand a multitude of voltages a motor may have, regardless of the environment.
VFDs, just like soft starters, have configured Fieldbus Network capability, and are additionally equipped with expandable inputs and outputs, or I/O. These allow you to expand the functionality of the drive, creating the ability to send more signaling between drives and other automation equipment without the requirement of a network.
Comparing Soft Starters and VFDs
Despite their similarities, there are a multitude of factors that should be considered when choosing between soft starters and VFDs.
Control
Soft starters and VFDs are both equipped with Fieldbus connectivity and are rated for multiple voltages and a variety of environments.
However, soft starters control the smooth starting and stopping of electric motors, but have no control over the speed at which the motor runs; the only options are on or off.
VFDs, on the other hand, can be programmed to control both the speed and torque of the motor they are connected to; they are also equipped with expandable inputs and outputs. These options allow for more flexibility and a wider amount of applications.
Energy
While both soft starters and VFDs are known to be power efficient, VFDs are generally better for saving power. Their ability to control speed and torque allows you to save on excess power, and they can run motors below the standard rate of 60Hz.
Cost
In general, soft starters are a less expensive option due to their more limited features. Depending on the size and power you are looking for, they can range anywhere from $350-$1,000 or more.
VFDs are usually a more expensive option, with prices varying depending on the horsepower and voltage required, as well as what application-specific requirements are needed. A basic low-horsepower drive can start around $500, but with added features and increased horsepower, the average price can extend into the thousands.
It’s worth noting that while VFDs may be more costly upfront, the power efficiency that they provide can lead to energy savings in the long run.
Size
Soft starters tend to be smaller and more compact than VFDs. Since they are essentially stopping and starting the motor, and nothing beyond that, they don’t require the memory features seen in some VFDs, which can reduce their footprint in some instances.
With greater programming capability and a higher horsepower threshold, VFDs are generally a bit larger.
Soft Starter vs. VFDs: Maximize Your Efficiency
Soft starters and VFDs both have specific applications; which one is right for you is ultimately dependent on your current equipment, motor size, horsepower, and other important factors.
Remember to consider the amount of space you have in your facility, the connectivity you require, and how much control you want over your motors. Is energy efficiency important? Is cost a major factor?
At HESCO, we aim to provide you with the guidance you need. Modernizing your facility to operate at full efficiency is crucial and we want to equip you with the tools you need to achieve that. Contact us today so we can help you choose between a soft starter and a drive to ultimately maximize your motor efficiency.