Soft Start vs Hard Start – What You Need to Know for Optimal Motor Performance

For any motor traditionally used in industry, one critical aspect of performance harnessing is the start-up. For electric motors, consumers are often presented with the choice between a soft start and a hard start to achieve optimal results. Both provide advantages and disadvantages in terms of motor performance, power consumption, and ease of installation, but how do you know which one to choose in a given application? This blog post explores the intricacies between soft starts and hard starts and aims to help you decide the best start-up method for optimal motor performance.

Quick Explanation of Key Question

A soft start slowly increases voltage when starting a motor, while a hard start increases voltage quickly. Depending on the motor, either one may provide better performance, so it is important to consult with an expert in order to determine the best option for your needs.

Introduction to Soft Start and Hard Start

Understanding the differences between soft start and hard start is essential for optimal motor performance. Soft start and hard start are methods used in electrical engineering which help to slowly increase voltage to an electric motor over time. The goal of both techniques is to reduce the amount of inrush current that flows into the motor, which helps protect the motor from any damage or stress during startup.

Soft starts allow voltage to gradually build up over a few seconds while hard starts send full voltage to a motor almost immediately. The difference between these two techniques has sparked debate among industry professionals as each method provides certain advantages and disadvantages. Advocates of soft start note how it can help prolong the life of motors by reducing the amount of power they receive at initial startup. Additionally, some motors contain delicate parts that can be damaged by the sudden jolt of power provided by a hard starting technique. On the other hand, proponents of hard starts point out that soft starts can add complexity to a system due to the need for additional relays, contactors, resistors, or SCRs (silicon controlled rectifiers). They also note that more time is necessary for a soft start since it must take place before any normal operation may occur.

This section has provided an introduction to soft start and hard start technologies so that their differences and potential impacts on optimal motor performance can be better understood. The coming section will explore the specifics behind “What are Soft Start and Hard Start?” in further detail.

  • A soft-start motor is able to move from a standstill to full running speed in around 1.5 seconds, whereas a hard-start motor is typically slower – taking 7 or more seconds to reach full running speed.
  • Soft-start motors require less current/amperage than hard-start motors, reducing costs and potential damage to nearby equipment.
  • The use of soft-start motors has been known to extend the service life of electrical components, as they reduce the mechanical stress associated with traditional hard-start motors.

What are Soft Start and Hard Start?

Soft Start and Hard Start are terms used to describe the method of starting an electric motor. A Soft Start gradually increases the speed of the motor, allowing it to accelerate slowly. This allows for reduced in-rush current, protection of the motor’s winding cables, and extended life of the motor’s components. A Hard Start instantly brings a motor’s power to its maximum level, providing more power with fewer parts but posing a greater risk that something will be damaged by the high initial current.

Both approaches offer advantages and disadvantages. Soft Starts typically last longer than Hard Starts but require more power; they also require additional wiring and components when compared to hard starts. On the other hand, hard starts offer quick results with less cost for installation and wiring; however, their shorter lifespan makes them more expensive in the long run as they must be replaced more often.

Ultimately, customers must weigh their own set of needs and budget against these two options when deciding which approach is best for them. Now that we understand both types of start methods, let’s look further into how a Soft Start works.

Most Important Summary Points

The Soft Start and Hard Start methods of starting an electric motor serve as two different approaches for their own benefits. Soft Starts tend to be more expensive but last longer, while Hard Starts are cheaper with a shorter lifespan. Customers must evaluate their individual needs and budget when deciding which approach is best for them. An overview of how a Soft Start works is then discussed.

How Does a Soft Start Work?

A soft start is a type of motor acceleration system that requires reduced voltage to begin operation. Rather than switching on and off abruptly, a soft start allows the voltage to be staggered as the motor begins and ramps up to speed. The benefit of this approach is twofold: it eases the stress on the motor from high inrush current at startup, and it increases efficiency during operation by reducing the amount of energy needed for starting.

Soft starts employ a variety of methods to reduce voltage during startup, including resistive taps or steps, internal resistors and/or inductors, or thyristor-based controllers. Each method has its own advantages and drawbacks. For example, resistive taps are fairly inexpensive but may require manual adjustment over the course of time due to aging components. On the other hand, thyristor-based controllers are more expensive but they can be calibrated to achieve very precise voltage control which helps protect against overheating when starting.

No matter which method is used, soft starts all share one primary benefit: they reduce stress on both the motor and power supply by creating smoother transitions as it accelerates from rest to full speed. This helps to reduce wear on components while also increasing overall system efficiency. As such, for applications requiring frequent restarts or repetitive operations where stress reduction is paramount, using a Soft Start is definitely recommended.

Now that we understand how Soft Starts minimize voltage and current flow on motors during startup, let’s review some benefits of reducing those flows even further with our next section that focuses on “Reducing Voltage and Current Flows”.

Reducing Voltage and Current Flows

The main difference between a soft start and a hard start is the way they impact voltage and current flows when they are used to power an electrical motor. When a motor is powered by a hard start, the system suddenly experiences an immediate peak in the amount of electricity running through it. This quickly creates large increases in the amount of current flow and voltage, causing the motor to be susceptible to a number of different issues.

Soft starts are specifically designed to prevent these issues by slowly ramping up the amount of current and voltage in order for it to reach its full power level. Over time, current flow and voltage increase more gradually, which lowers risk for damage due to sudden fluctuations. Temperature also increases more steadily using soft starts as opposed to hard starts, which can help maintain machine performance levels over extended periods.

In addition, soft starts provide some extra flexibility when it comes to controlling voltage at specific levels or percentages. Many commercial operations require certain machines to operate within a targeted range of parameters; with soft starts, this range can be effortlessly adjusted compared to utilizing hard starts, allowing businesses to fine tune their equipment.

Finally, one of the main advantages soft starts offer is that they reduce peak currents by up to 80 percent compared with hard starts – dramatically decreasing wear and tear on motors while also saving money on energy costs across the board.

By reducing voltage and current flows through managed ramping processes, soft start devices can not only extend motor lifespans but also provide operators with added options for customizing machinery performance levels. With these advantages in mind we next turn our attention towards exploring other benefits that these devices confer onto businesses who utilize them for powering their electrical motors.

Next we explore further in our discussion about how soft start technology provides additional benefits over traditional hard starting processes – including enhanced safety features, reliable operation and energy efficiency.

Benefits of Soft Start Over Hard Start

Soft start motors offer an array of benefits over hard start motors, some of which outweigh the costs associated with soft start systems. Most notably, soft starts extend the lifespan of a motor. Instead of dealing with a large surge of current that a hard start requires, the resistive nature of a soft start allows for an easier flow of current throughout the motor’s life. This helps avoid damage to components, particularly electronic components within the motor overall.

Another benefit of using a soft start is the fact that they reduce inrush current peaks. Inrush currents can sometimes be five to seven times larger than rated motor current and can cause serious issues in terms of power quality. By using a soft starter, the inrush current can be reduced by 50-95%, providing a better measure of power quality for both the user and their utility provider.

Of course, many soft starters also feature overload protection. With this added feature, extra protection is provided from thermal overloads and short circuits; this provides circuit protection against faults that can result from high starting currents caused by excessive static friction or mechanical problems with the motor’s load or drive train.

The cost associated with adding a soft starter to an industrial plant must be weighed against its benefits; however, it’s important to remember that these cost savings are often offset by additional energy savings and reduced maintenance costs due to increased motor life expectancy.

On the other hand, there are cases where the cost of installing a soft starter may not make economic sense. If space is limited, hard starting may be more suitable depending on system requirements; similarly, certain applications that require frequent startups should also consider avoiding using a soft starter since this might lead to unexpected downtime or an unnecessary overhaul when too much wear and tear has been accumulated over time.

Considering these pros and cons helps to identify situations in which a soft starter would offer superior performance over hard starting. Moving forward, we’ll dive deeper into how lower heat generation affects both options when choosing between Soft Start vs Hard Start for optimal motor performance.

Lower Heat Generation

Lower Heat Generation is one of the main advantages of using a soft start over a hard start. Soft starts work by gradually increasing the voltage and current to the motor, thus lowering its heat output on start-up and throughout its operation. Additionally, the gradual increase of voltage and current during a soft start reduces mechanical stress on the motor components, further decreasing problems caused by overheating.

A hard start typically makes use of a full surge of power, so the increased voltage and current can generate too much heat in motors that aren’t designed for it. Besides shortening motor life due to heat damage, extreme levels of heat can also place unnecessary load on a motor’s control systems and overload or trip circuit breakers which may require costly repairs or replacements.

In contrast, soft start technology helps limit these problems with less wattage lost as heat and fewer cycling operations per hour resulting in longer allowable class 10 starter running times. This ultimately equates to an increase in efficiency and cost savings due to lower energy costs from reduced heating.

Considering lower heat generation as a whole, investing in a soft start system may be beneficial to end users who are dealing with sensitive motors and want to preserve their performance over time.

Next up, we will discuss the various applications where soft starts offer superior performance compared to hard starts.

Applications of Soft Starts

The use of soft starts are virtually limitless in industries that require precise control and safety for motors. They are most commonly used for conveyor belts, pumps, turbines and large production machines that can require extended periods of running or intermittently starting or stopping. For any motor driven application that requires precise control or quick stopping, soft starts are an excellent option.

The advantage of these devices lies in their ability to provide a smoothly accelerating starting torque while preventing the harmonic distortion found in other start options. This creates far less stress on the motor itself and avoids sudden power interruptions when starting and stopping, increasing the life span of both the motor and related parts. Additionally, not only does this approach reduce wear-and-tear on equipment, it also saves costs in terms of maintenance and production efficiency.

On the other hand, when using a Soft Starter there is also one disadvantage: While they offer a smoother acceleration than traditional starters, this could potentially increase start-up time from under half a second to several seconds depending upon the load and technical parameters configured within the Soft Starter device. However this is often offset by the many benefits associated with using a Soft Start; such as improved functionality and performance management of machinery, increased safety for personnel and reduced energy consumption during operation.

Therefore, overall Soft Starters have many advantages over traditional starting methods in various applications and situations due to their ability to efficiently reduce both energy consumption and component wear while offering enhanced usability. This leads us into our next section which will review the cost analysis of installing soft starts vs hard starts.

Soft Start Cost Analysis

In any industry, understanding the cost difference between soft start and hard start technology is crucial when determining the optimal motor performance. Soft start implementations vary in price depending on factors such as motor size and application; however, these costs are generally lower than the upfront costs associated with setting up a hard start system.

When purchasing new equipment, it is important to look at the long-term costs of both soft start and hard start technologies. Generally speaking, soft start systems are cheaper to install since they require fewer components, less wiring and only one power source. In addition, they typically do not require extra maintenance or service after initial set-up and can be used with existing motors without having to upgrade them. Furthermore, when using soft start systems to manage larger motors, customers save money even more since they consume less energy with each individual cycle—saving money over time on electricity bills.

On the other hand, hard start requires more components upfront including contactors and voltage compensators. Additionally, installation of these systems is often times more expensive than soft starts due to their complexity, making them more difficult to install correctly. Moreover, when dealing with large motor loads, it is necessary to use a larger contactor in a hard start setup which result in incurring additional costs for upgrades.

Overall, for most applications soft start technology proves less costly than its hardstart counterpoint due to fewer upfront components needed along with the additional savings from reduced energy consumption levels. This cost analysis should be taken into consideration when determining the best motor performance solution for a particular application in order to achieve maximum efficiency and savings down the road.


Having evaluated both sides of the cost argument for a soft start versus hard start implementation when considering optimal motor performance, we can now evaluate other notable differences between the two solutions before drawing our conclusion in the next section.


The decision to use either a hard or soft start is an important one, as it will have a significant impact on the performance of motors. The conclusion that can be drawn is that the most suitable option depends on the specifics of the application.

Soft starts are recommended for applications with long running times, low power requirements, or when frequent starting/stopping is required. Although initial installation may be more expensive and energy costs during running may increase slightly, there will be fewer associated maintenance costs over time. Soft starts are also ideal for motor overload protection and limit their current draw and heating during acceleration.

On the other hand, hard starts are suitable for applications requiring a higher punch of power in order to start fast. This often includes pumps, conveyors, and similar machinery which need a quick burst of torque to get going immediately. Further, intermediate stop/start operations tend to be more economical using hard starts due to reduced energy cost as well as energy savings from avoiding heat generation within the motor winding itself. Additionally, using a hard start could allow you to avoid any issues related to starting duties or load-balance calculations if you find yourself in a situation where both requirements cannot be met at the same time.

Ultimately, whether or not you choose a soft-start or a hard-start circuit will depend upon your specific application needs. Both options have certain advantages and disadvantages that must be weighed each time an appropriate control method needs to be chosen for optimal motor performance.

Answers to Commonly Asked Questions

Are there any drawbacks or challenges associated with implementing a soft start?

Yes, there are some drawbacks and challenges associated with implementing a soft start. First of all, a soft start increases the cost of the motor system because it requires additional components to regulate the current during the starting process. Furthermore, soft starts can also be more complex to install and require regular maintenance in order to ensure optimal performance. Additionally, soft starts may also increase energy consumption if not implemented with precision and regular monitoring. Finally, when dealing with high-power applications, such as those in industrial settings, a soft start can cause significant losses in the power generated before reaching the desired levels.

How does a soft start affect electricity consumption?

A soft start can have a significant impact on electricity consumption. When a motor is started with a hard start, the initial inrush of current is much greater than when it is started with a soft start, meaning that more energy is being consumed. With a soft start, the initial current is lower, which helps reduce the amount of electricity required for starting. This makes the motor more efficient and lessens the burden on the power grid. Additionally, because the current is slowly increased over time with a soft start, the motor ramps up more slowly leading to less stress on components and less mechanical wear. This reduced wear and tear also further contributes to energy savings over time.

What kinds of applications benefit most from a hard start?

Applications that require a quick start-up, such as HVAC systems, pumps and compressors, are the ones that benefit most from a hard start. This is because they need to reach their full speed quickly in order to get the job done efficiently. Hard starts provide these types of applications with an immediate boost of torque to get them up and running quickly. Additionally, when a motor is switched off, it tends to lose its stored energy. A hard start helps restore this lost energy and replenish the motor’s reserves so it can reach its highest potential in less time. This makes hard starts ideal for applications where speed and efficiency are essential.