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Buyers Guide on Electrical Soft Starters

A motor soft starter is an electrical motor control device that regulates the starting and stopping of electric motors. They help in reducing the high inrush currents that occur during motor startup, which can cause stress on the motor windings and other connected equipment. In this buyer's guide, we will explore the various aspects of soft starters to help you make an informed decision when purchasing one.

Understanding Soft Starters

To grasp the functionality of soft starters, it's important to understand their basic operation. Soft starters gradually ramp up the voltage supplied to the motor during startup, resulting in a smooth and controlled acceleration. This reduces mechanical stress on the motor and minimizes electrical disturbances in the power supply network. Soft starters also provide protection against motor overloads and voltage fluctuations.

In addition to electrical soft starters, there are alternative solutions for achieving soft starts, such as mechanical options that rely on physical and mechanical mechanisms rather than electrical current.

Mechanical soft starters utilize clutches and various couplings that utilize fluids, steel shot, or magnetic forces to decrease the torque applied to the motor. By limiting the power surges and enabling a gentler and smoother power-up process, these mechanical solutions offer an alternative approach to achieving soft starts.

Benefits of Soft Starters

Soft starters offer several advantages for both the motor and the overall electrical system. Some key benefits include:

  • Reduced wear and tear: By gradually increasing the voltage, soft starters minimize mechanical stress on the motor and its components, prolonging their lifespan.

  • Energy savings: Soft starters prevent high inrush currents, which can lead to increased energy consumption. By reducing the current spikes during motor startup, energy costs can be significantly reduced.

  • Smooth operation: The controlled acceleration provided by soft starters ensures smooth motor operation, eliminating sudden jerks or shocks.

  • Improved system reliability: Soft starters protect the motor against overload conditions, voltage fluctuations, and other electrical issues, thus enhancing the overall reliability of the system.

Key Features to Consider

When selecting a soft starter, there are several important features to consider, such as:

  • Current rating: Choose a soft starter with a current rating suitable for your motor's requirements.

  • Voltage compatibility: Ensure that the soft starter is compatible with the line voltage level of your electrical system.

  • Protection features: Look for soft starters that offer comprehensive protection features, including overload protection, short circuit protection, and phase loss protection.

  • Communication capabilities: Some soft starters come with communication options like Modbus or Ethernet, allowing for remote monitoring and control.

  • User interface: Consider the ease of use and functionality of the soft starter's interface, including display screens, buttons, and programming options.

Types of Motor Soft Starters

There are different types of soft starters available, each with its own unique characteristics. Common types include:

  • Voltage ramp soft starters: These gradually increase the voltage supplied to the motor over a predetermined time, resulting in a smooth startup.

  • Current limit soft starters: These limit the current supplied to the motor during startup, preventing excessive current draw.

  • Torque control soft starters: These regulate the torque output of the motor during startup, providing precise control over acceleration.

  • Combination soft starters: These combine the features of voltage ramp, current limit, and torque control to provide a versatile solution for various motor types and applications.

What Are Some Common Applications of Soft Starters for Motors?

Soft starters can be used in various industries and motor-driven systems where controlled motor startup and protection are essential. Here are some applications where soft starters are widely used:

  • Pump Systems: Soft starters are frequently employed in pump systems, such as water supply pumps, irrigation pumps, and wastewater pumps. They ensure smooth startup and prevent water hammering or sudden pressure surges in the system.

  • Conveyor Systems: In industries like manufacturing, distribution, and mining, conveyor systems play a vital role in material handling. Soft starters help in smoothly starting and stopping conveyor motors, reducing stress on the belts and other mechanical components.

  • HVAC Systems: Soft starters are commonly used in heating, ventilation, and air conditioning (HVAC) systems, particularly for fans and blowers. They provide a gradual increase in motor speed, preventing sudden drafts or excessive airflows during startup.

  • Compressors: Soft starters are employed in compressor systems used in industries like refrigeration, air compression, and pneumatic tools. They ensure controlled acceleration of the compressor motor, reducing strain on the system and minimizing pressure fluctuations.

  • Centrifugal Machines: Soft starters are utilized in centrifugal machines such as industrial mixers, crushers, and separators. They enable smooth acceleration of the motor, avoiding sudden jolts or vibrations that could impact the operation of the machine.

  • Machine Tools: Soft starters are commonly used in machine tools, such as lathes, mills, and drills. They ensure a smooth and controlled startup of the motor, minimizing tool wear and providing precision in machining operations.

  • Industrial Fans: Soft starters are employed in industrial fan applications, including exhaust fans, cooling fans, and ventilation systems. They allow for a gradual increase in fan speed, reducing mechanical stress and providing precise airflow control.

  • Crushers and Shredders: Soft starters are utilized in crushers, shredders, and other size-reduction equipment. They facilitate controlled motor acceleration, preventing sudden load surges and enhancing the overall efficiency of the crushing or shredding process.

  • Lifts and Elevators: Soft starters find application in lift and elevator systems, ensuring gentle acceleration and deceleration of the motor. This helps in providing a comfortable ride for passengers and reducing wear on the mechanical components.

Selecting the Right Soft Starter

To choose the right soft starter for your application, consider factors such as motor type (whether it is for single-phase or three-phase motors), horsepower rating, starting torque requirements, and the nature of the load. Consulting with a knowledgeable supplier or electrician can help you determine the most suitable soft starter for your specific needs.

Installation and Wiring Guidelines

Proper installation and wiring are crucial for the effective operation of soft starters. Follow the manufacturer's guidelines and adhere to local electrical codes to ensure a safe and reliable installation. Pay attention to proper grounding, wire sizing, and connection techniques to avoid potential issues.

Maintenance and Troubleshooting Tips

Soft starters generally require minimal maintenance, but regular inspections and checks are important to ensure optimal performance. Keep the soft starter clean and free from dust or debris. Familiarize yourself with the troubleshooting guidelines provided by the manufacturer to address any operational issues effectively.


Soft starters offer significant benefits in terms of motor protection, energy savings, and overall system reliability. By understanding the various features, types, and considerations associated with soft starters, you can make an informed decision when purchasing one for your specific motor application. Remember to consult with knowledgeable suppliers or electricians who can provide valuable insights and guidance in choosing the most suitable soft starter for your specific needs.

Proper installation, adherence to wiring guidelines, and regular maintenance are crucial for maximizing the benefits and longevity of your soft starter. Ready to enhance the performance and protection of your motor? Explore our wide range of soft starter models and make an informed choice today. Shop for electric motor soft starters at the Blackhawk Supply store!

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