When to Use a Soft Starter – Benefits and Applications

Soft starters are becoming increasingly popular in industrial electrical systems due to the many advantages they offer. While traditional starters and capacitor start-and-run motors work just fine, the extra power and control that soft starters bring to the table make them well worth considering. But what are those advantages and what types of applications are best for using them? In this post, we’ll take a deeper dive into soft starters and explore exactly when to use them and what benefits they can offer. Get ready to become an expert on soft starters and discover which applications are right for taking advantage of them!

Quick Recap

Soft starters provide motor protection by limiting the inrush current during startup, which helps extend the life of electrical components. Additionally, they reduce mechanical wear and tear on machinery by providing a smooth start up with lower torque.

What is a Soft Starter?

A soft starter is an electrical device used to control the acceleration and deceleration of an electric motor by gradually increasing or decreasing voltage over time. The purpose of this device is to minimize the mechanical and electrical shock that can occur when switching motor power on and off abruptly. Throughout the entire process, the motors remain powered, which reduces wear and tear greatly, thus prolonging its lifespan.

Soft starters can be particularly beneficial in applications with heavy loads, where abrupt starts and stops can lead to mechanical damage as well as wasted energy. This makes them popular within a range of industries, from industrial manufacturing to consumer electronics. In addition, they also help reduce excessive strain on utility grids and other electricity-consuming infrastructure due to sudden changes in demand.

On the other hand, there are some drawbacks associated with soft starters (such as increased complexity and cost) that must be taken into consideration before implementation. Additionally, certain motor types may require different voltage profiles for starting, so careful analysis of their specifications may be necessary.

In conclusion, soft starters provide numerous benefits in appropriate applications, but care should be taken to ensure they are properly integrated with compatible motor types. With that said, we will now move on to our next section—Soft Starter Hardware—where we will discuss the components necessary for using soft starters effectively.

Soft Starter Hardware

Soft starters are built with a variety of components, such as resistance starters, contactors, and/or other control units. Depending on the complexity of the system and the application, additional components may be required to ensure reliability and performance.

For example, a resistance starter soft starter uses resistors to reduce inrush current by gradually increasing voltage to the motor during start-up. This type of soft starter is ideal for motors with high starting loads, but can be expensive and require more maintenance than other types of soft starters because the resistors may need to be replaced regularly.

Contactors are often used to control the supply of power to a motor. By using separate contactors for typically each phase, larger motors can start and run efficiently without an overload of current or caused damage due to excessive heat. This type of soft starter is especially useful for applications where variable speeds are required or engines may need to come back online after prolonged periods without use.

Finally, additional control units may be necessary for sophisticated systems that require frequent feedback from the motor or that have varying environmental conditions which may affect their operation. These units increase the complexity – and cost – of the system but may be necessary depending on the application.

Soft starter hardware can provide many benefits when applied correctly, however considerations must be taken into account when determining what type of components, if any, are needed to power an industrial system efficiently. With this being said, understanding how these components interact with each other is essential in order to optimize overall performance and extend equipment life. In the next section we will explore how these components work together during soft starter operation and how they contribute to their effectiveness in regulating motor speed and load profiles.

Soft Starter Operation

Soft Starter Operation involves controlling the torque, current, and speed of an AC motor by using a controlled voltage applied to the motor. The Soft Starter also gives an adjustable time-based ramp up of the motor voltage, allowing for smoother operation. This reduces current and torque draw on startup, as well as wear and tear on the motor and associated equipment parts. Soft Start Operation is seen in a wide variety of applications, such as pumps, fans, grinders, blowers, and more.

The debate between Soft Start Operation vs No Soft Start centres around convenience versus cost. For starters, using a Soft Starter requires more installation time and effort due to wiring the device into the existing system. This raises up front costs and causes some disruption during the installation phase. Conversely, running a motor with no Soft Starter can be simpler but at the expense of higher start up currents that cause mechanical stress or damage to drive components in the long run.

Overall, there are pros and cons to either method but making an educated decision on whether to use a Soft Starter comes down to evaluating the costs and benefits for each individual application. Moving forward into the next section we will explore some of these benefits in more detail.

Essential Highlights

Soft Start Operation is used to control the torque, current, and speed of an AC motor by applying a controlled voltage. It reduces the strain on a motor and associated components during startup, however it does require more installation time and added costs. Ultimately, when deciding if soft start operation should be used or not, the overall costs and benefits need to be taken into consideration for each individual application.

The Benefits of Using Soft Starter

When deciding between traditional motor starting methods and using a soft starter, there are many benefits to consider. A soft starter can provide improved reliability and performance of the motor, as well as increased energy efficiency. Installing a soft starter can significantly reduce the inrush current associated with traditional motor starting methods, while preventing power quality issues such as voltage sags and harmonic distortion. In addition, a soft starter also offers a number of other advantages compared to other starting methods, including lower operating costs and improved protection against electrical shock.

Some organizations may be hesitant to invest in the technology required for soft starters, arguing that AC motors are already quite reliable when started with star-delta or auto-transformer arrangements. It is true that these traditional starting techniques do provide reliable operation; however, they can cause potentially damaging inrush currents and result in a great deal of stress on both motors and electrical components over time. Soft starters provide a more controlled start up process which could arguably prevent some of this damage from occurring in the long run.

In general, investing in soft starters can provide noticeable energy savings over traditional motor starting methods. Motors started with a soft starter tend to operate at lower temperatures, leading to fewer problems over time and longer operating life. Ultimately, choosing to use a soft starter pays off not only in terms of initial cost savings but also through long term reliability.

All the benefits of using a soft starter point towards increased protected against motor overloads failure. The next section will discuss how using a soft starter results in greater motor overload protection during operations while introducing recent innovations available in this area of motor systems technology.

Motor Overload Protection

When it comes to motor overload protection, soft starters offer a great advantage. They provide protection against voltage and current fluctuations, as well as excessive operating temperature. With their built-in temperature sensors, they can respond quickly when motor overload occurs. This helps to avoid unplanned downtime due to equipment failure. Not only do they protect the motor from excessive loads and temperature, but they can also extend its lifetime significantly, since they allow the motor to warm up gradually before it reaches full operating capacity.

There are two sides to this debate. On one hand, some argue that soft starters may not be the ideal solution for all applications needing overload protection due to their cost and complexity. On the other hand, supporters argue that their benefits far outweigh any associated costs or complexities. Soft starters are often preferred over alternative methods because of their precise control and built-in monitoring capabilities which can help reduce downtime due to equipment failure.

Overall, soft starters provide an effective means of motor overload protection in many applications ranging from oil refineries and paper mills to water treatment facilities and data centers. Regardless of the application, they are an essential tool in any maintenance engineer’s toolkit.

Moving on to energy efficiency, most modern soft starters offer many ways to help conserve energy, such as speed control and torque ramping capabilities. These features can reduce peak energy demand and total energy consumption over time, helping businesses reduce their energy costs while maintaining efficient operation.

Energy Efficiency

Energy efficiency is a key factor to consider when choosing a soft starter. Compared to a standard motor, a soft starter saves energy by minimizing the inrush voltage used when starting the motor. By using less energy to start the motor, it reduces overall power consumption and can increase an electrical system’s efficiency significantly. It also allows motors to run at full speed with reduced current.

The debate about energy efficiency lies in whether or not the energy savings achieved through soft starting make up for the costs associated with purchasing and installing the device itself. Some professionals claim that a soft starter may not be able to recuperate its own costs due to the related energy savings, but others point out that energy savings vary based on individual applications, so some systems may need more than five years to break even.

Regardless of one side or the other of this debate, investing in a soft starter can prove beneficial in increasing energy efficiency in an electrical system. Its controlled acceleration reduces peak current and helps maintain a steady flow of current throughout operation. This helps reduce damaging surges, overheating and wear on components, all of which results in an overall increase in efficiency.

Next, we’ll explore what types of applications are typically suited for soft starters and how they can benefit industrial operations.

Suitable Applications for Soft Starter

Soft starters are an important tool for a variety of industrial processes, and selecting the right application is essential. There are many suitable applications for using a soft starter, such as motor-driven equipment that require long start times, large load currents and frequent starting cycles. Soft starters can also be used to protect motors from mechanical shocks or sudden stops due to external cuts in the electricity supply. Furthermore, they offer several speed control benefits which can reduce wear on the motor and provide smoother production as well as energy savings.

Conversely, some processes may not be appropriate for using a soft starter since the cost associated with purchasing, installation and maintenance are higher than those of other types of starters. Additionally, certain specialized motors may require special software to work in conjunction with a soft starter, making them more complex to use than traditional solutions.

It is important to do an assessment of all aspects before deciding on the best solution when implementing a soft starter in any given application. Ultimately, there are many suitable applications that could benefit from the advantages offered by using a soft starter; however, understanding these applications along with their inherent limitations should be taken into consideration before investing in this technology.

Having discussed suitable applications for using a soft starter, the following section will investigate the cost associated with using this type of motor starter.

The Cost of Soft Starters

When considering the cost of soft starters for motor control applications, the total lifetime costs must take into account the initial purchase price and any maintenance costs. Initially, a soft starter might appear to be more expensive than other traditional starter types such as manual or electronic starters. However, this is not necessarily true when looking at the long-term cost savings of a soft starter for its many benefits. Soft starters can help to reduce wear and tear on motors, as well as lead to energy savings over time.

In fact, with energy savings between 5-35%, depending on the application and environment, soft starters can quickly pay for themselves over a few years due to decreased energy bills. Heat generation in both motor and soft starter are also reduced significantly which impact running costs. Additionally, some employers may offer financial incentives or lower tax rates for using energy efficient alternatives, providing even greater value to businesses adopting soft start technology.

Overall, while a potential higher purchase cost may lead to an initial hesitation when considering making the switch to a soft starter, the long-term cost implications can often make a strong case for utilizing this type of motor control solution.

Next, it is important to understand how circuit design considerations such as voltage and current should be taken into account when designing a system that employs soft starters. In the next section we will cover circuit design considerations that should be taken into account when incorporating soft starters into systems.

Circuit Design Considerations

Circuit design considerations are important when deciding whether to use a soft starter in an application. The protection of the motor and its system is critical, and all elements must be considered when designing the circuits.

Considerations around levels of overload protection and current adjustment should be explored – both by using a soft starter, or other circuit protection and control elements. For starters with single phase capabilities, the importance of the auxiliary components must not be overlooked as these may act as a supplementary circuit breaker. For starters with three-phase capabilities, adjustable current limiters and adjustable restart times may also be used to account for system changes such as increased current lag from long distance wiring runs.

The overall efficiency of the solution must also be taken into consideration. While starting with soft starters may be less costly than designing for full voltage across the motor, there are limits on current that can be drawn from each phase depending on the particular machine being used and its internal windings. Therefore, if proper safety considerations are not accounted for through circuit design, damage to other electric components or even potential fire hazards could occur if too much current is drawn from one phase or another during startup or shutdown.

In addition to the necessary considerations related to electrical safety, thermal requirements should also be examined. Soft starters draw more heat energy during motor startup phases than direct on line starters do, so ample ventilation should be provided in surrounding areas to prevent overheating of adjacent components and ensure consistent uptime performance. Furthermore, it is important to consider how often the soft starter will need to restart; as increased frequency typically leads to increased heat generation over time that should also be accounted for in any thermal designs associated with the application setup.

Designing a circuit with a soft starter should not be taken lightly – considering motor ratings and load conditions along with load type (e.g., induction motors), voltage availability, wiring configurations and total wattage of devices connected is necessary for proper operation for many applications. Fortunately, consulting with trained professionals such as experts in industrial automation or equipment service companies can help make sure every factor is taken into account before investing in any specific electrical system design involving a soft starter installation.

Having discussed circuit design considerations related to a soft starter installation, let us now turn our attention towards looking at available supply voltage and current values required when using these types of devices in various applications.

  • Soft starters can reduce peak inrush current by 80-95% compared to direct on line starters.
  • Soft starters can provide motor torque control, optimized start and stop times, reduced maintenance costs by minimizing mechanical wear and tear on motors and driven equipment.
  • Soft starters also provide energy savings of 15% or more for motor circuits due to reduced operating losses and improved power factor levels.

Voltage and Current Value

When utilizing a soft starter, voltage and current values play an important role in providing efficient control. Voltage and current profiles can be adjusted to ensure the motor starts slowly, reduces peak inrush current, and avoids high mechanical stress due to the over torquing of start motors. This can increase the longevity of the motor’s life while operating more efficiently.

On the other hand, decreasing dynamic torque capabilities can also result from using a soft starter, limiting the speed of production. Additionally, depending on the application and voltage range requirements, adjustable frequency drives may be better suited for heavy-duty applications that require very large motors since they offer improved flexibility and control.

Along with adjusting voltage and current values to optimize performance, another important factor of using a soft starter is its ability to adjust speed and torque according to various motor load conditions. In the next section we will explore how a soft starter provides adjustable speed and torque features which can enable smoother acceleration and deceleration for motors.

Speed and Torque Adjustment

Soft starters offer the ability to adjust speed and torque as needed while in operation. This can provide significant benefits to operations that need to make frequent adjustments, as well as those that are attempting to reduce costs. On the other hand, this feature can also introduce potential problems, especially when the necessary maintenance is not regularly performed.

In terms of benefits, adjusting the speed and torque of a motor allows for greater energy efficiency. If a machine does not require full power for a certain task, then the soft starter is able to match the level of power to match the specific needs. This results in reducing energy consumption and lower operational costs. Additionally, it allows for smoother acceleration and deceleration when starting or stopping a machine or process, which reduces mechanical wear over time. Similarly, soft starters also reduce electrical stress on equipment since voltage spikes can be reduced during start-up and slow acceleration speeds.

On the flip side of the coin, using a soft starter for speed and torque adjustment requires frequent maintenance so the feature remains reliable. Many seep devices use mechanical components rather than digital solutions that operate without wear-and-tear due to constant use. Therefore, if regular maintenance is not performed, then this feature may become unreliable or even break down over time. As such, it is important to consult with an expert technician when selecting a softer starter solution so they can advise on proper maintenance schedules to ensure years of reliable operation.

Having considered both the benefits and drawbacks of using soft starters for speed and torque adjustment, what should you consider when using one? That will be discussed in the next section….

What to Consider When Using Soft Starter

When using a soft starter, it is important to consider a variety of factors in order to ensure optimal performance. These include the load being applied to the soft starter, the type of motor that is being used, and the electrical components available. Additionally, one should consider whether or not they are willing to sacrifice power efficiency in exchange for better protection.

The load being applied to a soft starter is key when determining its effectiveness. If too much load is applied, the soft starter will become overloaded and unable to provide sufficient voltage to the motor. On the other hand, if too little load is given to the soft start, it may not be able to properly reduce the voltage for an adequate start-up period. As such, it is important to calibrate the load accordingly in order for optimal performance with a soft starter.

The type of motor being used is also important when considering a soft starter system. Generally speaking, induction motors are better suited for soft starters as they produce a large amount of torque during startup which helps ensure a smooth launch. Conversely, permanent magnet motors are usually not well suited for a soft start system due to their much lower levels of torque during startup.

Finally, available electrical components must be taken into account when installing a soft start system. This includes selecting appropriate circuit breakers, controlling devices and wiring protection systems that can both safely handle the voltage produced by the motor and handle the high current pulse provided by a soft starter circuit.

While the use of a soft start system is beneficial in many circumstances due to its ability to provide ample protection for motors during startup and shutdowns as well as reduced wear and tear on parts, there are some situations where sacrificing power efficiency may not be acceptable tradeoff for better protection. As such careful consideration should always be taken before deciding on whether or not implementing a soft starter system is appropriate given all aspects of the specific situation.

Having considered these different variables when deciding whether or not to use a soft starter system, we now turn our focus towards reaching a conclusion on its benefits and applications.


The application of soft starters can provide many advantages that are cost-effective and reliable when used in the right situation. Although they may come with disadvantages such as additional noise or loss of power, they often offer an increased life expectancy to the mechanical components of the machine than conventional starters.

Soft starters are a useful tool for a wide range of applications. They can improve safety by enabling smoother starts, decreasing motor wear and tear, and improve the process control of your motor. Depending on the application, the installation and operational costs can be recouped over time due to reduced energy bills and maintenance costs. Soft starters also have some disadvantages such as additional noise or decreased power output, but these should not be a deterrent when weighing up their use in various industries and scenarios.

It is important to note that when selecting whether to use a soft starter or not, it is essential to consider the full scope of potential benefits, drawbacks, design considerations and long-term expensive concerns before making a decision on its use in an application.

Common Questions Explained

Are there any drawbacks to using a soft starter?

Yes, there are some potential drawbacks to using a soft starter. Because current and torque are reduced gradually when running from a low voltage operation, a longer time is needed to accelerate the motor to its rated speed. This can lead to motor overloading or higher energy consumption as the motor will have to work extra hard to reach its required torque. Additionally, the cost of a soft starter may be higher than that of other starting devices, making them less cost-effective in some applications. Finally, they may also cause increases in line voltage harmonics which can result in motor bearing failure or damage to other connected equipment.

What type of applications is a soft starter suitable for?

A soft starter is an electrical device that helps regulate the startup of motors by gradually increasing the torque to its running speed. This type of device is suitable for a variety of applications ranging from being used in HVAC systems, pumps, conveyor belts, rotating machinery, compressors and fans to domestic appliances and agricultural equipment.

Soft starters are ideal for large-scale industrial equipment due to their ability to provide a smooth start up and prevent disruptive jolts from slowing down or damaging heavy-duty machines. By providing gradual acceleration, soft starters enable engineers to adjust parameters such as voltage levels and ramp times to ensure that motors don’t use more energy than necessary during start up.

Soft starters can also be used in smaller applications where space may not permit the installation of a full motor control system. Additionally, they provide benefits over mechanical solutions such as star-delta starters due to their ability to reduce electrical noise, create high power factor motor control, adjust motor speed and efficiently control current peaks during start up.

What are the advantages of using a soft starter vs. a regular starter?

Soft starters offer a number of advantages over regular starters, including reduced current draw at startup, increased motor life, smoother acceleration and deceleration, and improved productivity.

The primary benefit of using a soft starter is reduced current draw. This makes it easier to protect against voltage drops and other issues related to sudden changes in load or power supply. By starting the motor slowly and ramping up its output gradually as opposed to immediately turning to full speed, motors can avoid drawing excessive current during start-up. This leads to reduced stress on the motor and improved reliability.

In addition to reducing the current draw, soft starters also provide more consistent starts that reduce wear and tear on the motor’s windings, resulting in greater overall motor life. Moreover, soft starters can limit the inrush current through an adjustable “accel rate” setting which eliminates motor overcurrents during start-up.

Additionally, because motors with soft starters start and stop at a constant, controlled rate, they provide smoother acceleration and deceleration of the driven machinery. This can help improve production throughput and overall facility productivity. For example, soft starting conveyors greatly reduces friction for quicker acceleration and deceleration which can increase productivity by allowing for faster line speed changes without any extra power requirements.

Overall, using a soft starter instead of a regular starter can significantly improve your system’s performance while saving money on energy costs associated with unnecessary power operations.