Soft Starters
Soft starters help reduce inrush current and mechanical stress on motors during startup. Ideal for conveyors, pumps, and HVAC systems, soft starters are essential in improving energy efficiency and extending motor life. At Wistex, we carry ABB and Eaton soft starters designed for industrial reliability and easy integration. Explore reliable 3-phase soft starters and low-voltage options for industrial applications.
Need help selecting the right soft starter? Contact our motor control experts.
Soft Starters We Offer
Wistex carries a wide selection of soft starters designed to reduce mechanical stress during motor startup and protect valuable equipment. Our inventory includes ABB soft starters, low voltage models, and 3-phase motor soft starters to meet the needs of industrial, commercial, and manufacturing applications.
3-Phase Motor Soft Starters
3-phase motor soft starters are specifically designed to optimize the startup process for three-phase induction motors. By gradually increasing voltage during motor acceleration, these starters prevent abrupt torque spikes, reducing system stress and improving operational efficiency.
Low Voltage Soft Starters
Enhance equipment longevity and reduce energy costs with low voltage soft starters. Deliver smooth motor startups, minimized mechanical stress, and overall improved system efficiency.
ABB Soft Starters
ABB soft starters deliver reliable motor control with advanced features like torque control, built-in bypass contactors, and energy-saving modes. Designed for smooth acceleration and deceleration, ABB models offer proven performance across a wide range of industries, from HVAC to water treatment.
What is a Soft Starter?
Definition and Purpose
Soft starters are electrical devices used with AC motors to control and reduce the stress of motor startup. A soft starter gradually increases the voltage supply instead of an immediate surge of full voltage, allowing for a smoother, more controlled acceleration. This process helps minimize electrical stress, reduce mechanical wear, and prevent 100% instantaneous torque that damages the motor or connected equipment over time.
By integrating a soft starter for efficient motor control, businesses can enhance motor performance while extending operational lifespan.
Benefits of Using Soft Starters
Using a soft starter offers several key advantages:
- Energy Efficiency: By limiting the initial power surge, soft starters help lower overall energy consumption, leading to cost savings.
- Extended Motor Lifespan: Reducing sudden torque and overheating minimizes wear and tear, helping motors last longer.
- Improved Operational Efficiency: With controlled acceleration, motors run more smoothly, reducing strain on electrical systems and mechanical components.
- Reduced Power Surges: Soft starters prevent high inrush currents, which can cause voltage drops and disrupt other electrical equipment.
- Adjustable Acceleration and Deceleration: Many soft starters allow users to customize startup and shutdown speeds to match operational needs.
Learn more about the benefits and applications of soft starters.
The Five Main Types of Soft Starters
Several types of soft starters are available, each designed to accommodate different motor requirements and operational needs. These devices help reduce electrical and mechanical stress during startup, improving motor efficiency and lifespan. Below, we’ll explore the five main types of soft starters and their applications.
1. Primary Resistor Soft Starters
Primary resistor soft starters are among the earliest soft starters, dating back to the early 1900s. As the name suggests, they use three resistors, one for each phase of the electrical current, to limit the inrush current during startup. Gradually increasing voltage allows for smoother motor acceleration. Once the motor reaches a set speed, a timer removes the resistors from the circuit, enabling full-power operation.
These starters provide two-point acceleration and are best suited for applications requiring limited torque, such as squirrel cage motors used in pumps and fans.
2. Autotransformer Soft Starters
Autotransformer soft starters are among the most efficient motor startup options. Instead of resistors, they rely on transformer windings with adjustable taps to regulate voltage and current. By selecting different taps, operators can control the amount of power sent to the motor, ensuring a smooth and controlled startup.
These starters are particularly useful for star or delta-connected three-phase induction motors, where maintaining low voltage while achieving maximum starting torque per line amp is critical.
3. Part Winding Soft Starters
With a part-winding soft starter, the motor windings must be divided into two or more separate sets intended for parallel operation. During start-up, power is only applied to one set of windings, but as the motor reaches speed, power is applied to the other set to resume normal running. Windings energized this way produce a reduced starting current and torque. Part-winding also minimizes voltage drop and excessive heat during start-up.
The part-winding method is ideal for motors that supply moving centrifugal force, such as pumps, fans, and blowers.
4. Wye-Delta Soft Starters
A Wye-Delta soft starter can only be used in motors with connection points to each of the three coil windings, specially wound with six leads for both Delta and Wye connections.
The Wye configuration - named such because of its "Y" shape - results in a line voltage connection that is applied to an electrically larger winding, helping to reduce the line current. After a pre-determined amount of time, the starter electrically switches these windings over to the Delta configuration - named for its resemblance to the Greek "delta" - during which the windings are connected normally, with every winding receiving full voltage.
There are two different types of Wye-Delta starters:
- Open Transition: The starter is placed at the transition point, where the motor must disconnect and reconnect when switching from Wye to Delta. This may cause a slight hitch in operation and allow some inrush current.
- Closed Transition: During the Wye to Delta transition, the motor is kept online using an extra contact and resistors. This eliminates any concerns about inrush, but the cost for these soft starters is slightly higher than for an open transition.
Wye-Delta starters are among the most common reduced voltage starters used in large horsepower and three-phase induction motors.
5. Solid-State Soft Starters
Solid-state starters are the most common overall, as well as the newest and most effective method, replacing mechanical components with electrical ones using a silicon control rectifier, or SCR. The SCR controls the motor's voltage, current, and torque during motor acceleration. It also can rapidly switch heavy currents, meaning the soft starter can provide smooth, step-less acceleration, which is considered the smoothest soft start method. A motor across the line (full voltage) will draw 5-7 times the rated amount of current for a brief timeline at start-up. This surge of current draws the power consumption up and is what you get charged for in your utility bill. The Solid State Starter (Soft Starter) controls this inrush current and reduces the electrical losses, saving energy costs and mechanical wear and tear.
Solid-state starters are most often used as AC motor starters in industrial applications, such as processing equipment, crushers, conveyors, elevators, mining, and more. They are also used in HVAC systems, on fans, pumps, and where constant volume is needed.
Applications for Soft Starters
Our soft starters are engineered for demanding environments where motor protection and smooth startups are essential. Typical applications include:
- HVAC Systems - Smooth operation of fans, compressors, and chillers
- Water and Wastewater Pumps - Controlled startups to prevent water hammer and pipe stress - Smooth operation of fans, compressors, and chillers
- Conveyor Belts - Gradual acceleration to reduce mechanical wear and system strain
Explore our full range of contactors and overhead relays to complete your motor control system.
Why Choose Wistex for Soft Starters & Motor Control Solutions
At Wistex, we offer a full range of industrial soft starters designed to ensure smooth motor startups and protect critical equipment. Whether you're managing HVAC systems, pumping stations, or manufacturing lines, our experts can help you find the right ABB soft starter for your specific application.
Why choose Wistex for soft starters?
- Trusted brands like ABB for proven performance
- Technical guidance to select the right starter based on horsepower, voltage, and environment
- Fast shipping on most in-stock soft starters
- Manufacturer-backed warranties for long-term reliability
Keep your motors protected and your operations running smoothly with help from Wistex.
Soft Starter FAQs
Learn more about how electrical contactors support safe, reliable motor control in industrial systems.
A soft starter reduces motor voltage during startup, minimizing mechanical stress and extending equipment lifespan
Sizing depends on motor horsepower, full load current, and application type. Contact Wistex for expert sizing help.
Smooth startups, reduced wear and tear, improved energy efficiency.
At Wistex, we offer a full range of industrial soft starters designed to ensure smooth motor startups and protect critical equipment. Whether you're managing HVAC systems, pumping stations, or manufacturing lines, our experts can help you find the right ABB soft starter for your specific application.
Why choose Wistex for soft starters?
- Trusted brands like ABB for proven performance
- Technical guidance to select the right starter based on horsepower, voltage, and environment
- Fast shipping on most in-stock soft starters
- Manufacturer-backed warranties for long-term reliability
Keep your motors protected and your operations running smoothly with help from Wistex.