Shop All Soft Starters

A Soft Starter is used to accelerate, decelerate, and protect three-phase induction motors. Soft starters limit the high inrush currents on motor startup. These solid-state starters incorporate thermal overload electric motor protection. Our WEG soft starters are available in three series: SSW07, SSW06, and SSW900. In addition, we also offer enclosed combination soft starters built-to-order by our panel shop.

Specifications

• 17 to 1400 Amps
• 3 to 1500HP
• 230, 460, or 570V Models
• Duty cycle: 300% FLA for 30 seconds, 10 starts per hour (with vent kit)
• IP20 Finger-safe terminal cover options
• Operates in ambient temperatures up to 131ºF (55ºC)
• Variety of wire ranges and stud hole sizes
• Built-in electronic thermal relay

What is a Soft Starter?

A reduced voltage soft starter helps protect the motor and connected equipment from damage by controlling the terminal voltage. This limits the initial inrush of current and reduces the mechanical shock associated with motor startup and provides a more gradual ramp up to full speed. Soft Starters are also beneficial to electrical systems with limited current capacity when using a soft starter for motor starting to limit the inrush current. By gradually increasing the motor terminal voltage the soft starter produces a more regulated motor acceleration up to full speed. Soft starters are also capable of providing a gradual ramp to stop where sudden stopping may create problems in the connected equipment.

Benefits of Using Soft Starters

• Provides speed ramping and torque control when desired during starting or stopping
• Limits high inrush currents associated with starting a large motor to avoid supply network issues or penalty charges
• Strong reduction on mechanical stresses over the coupling and transmission devices (gearboxes, pulleys, gears, conveyors, etc.)
• Avoiding pressure surges or ‘hammering’ in piping systems when fluid changes speed too rapidly
• Avoids “water hammer” in pump applications

Solid State

Our soft starters are solid state devices that feature electrical components instead of mechanical components. Solid state devices typically see greater lifespans due to no wear-and-tear from small moving components.

Enclosed Combination Soft Starters

We offer enclosed combination soft starters that include WEG soft starters installed in a wall mount enclosure. These enclosed combination starters also include other devices such as circuit protectors, start/stop pushbuttons, control transformers, and more.

Soft Starters are helpful in extending the life of a system by limiting mechanical shock. They ultimately give you more control over your AC Motors by allowing you to control the ramp up and even ramp down.

Where are Soft Starters Used?

Soft Starters are used in many types of applications due to the control they give operators. Some examples of applications that soft starters are typically coupled with include:
• Conveyor Belts
• Pumps
• Milling Machines
• Stone Crushers
• Mixers
• Fans
• Compressors

Who Uses Soft Starters?

Soft Starters see widespread use across many industries due to the wide array of applications that make use of them. Some industries that use Soft Starters include:
• Food & Beverage
• Textile
• Lumber
• Cement
• Mining
• Pulp & Paper Mills
• Sanitation

Do You Know Your Full Load Amps?

The Full Load Amps (FLA) rating of the soft starter must meet or exceed the FLA of the motor. To properly determine your soft starter needs, you must size the drive based on Amps:
• Identify the Full Load Amps (FLA)* of the motor
• Select the soft starter that meets or exceeds this FLA rating

Full Load Amps (FLA) refers to the current of the motor at its rated load and voltage. It is equal to the amps the motor draws while producing the rated output horsepower. For more information on determining your FLA,view the applicable section of this Knowledge Base entry.

Starts Per Hour

Another important factor when choosing your Soft Starter is the amount of starts per hour that you expect out of your application.

All WEG soft starters accommodate up to 10 starts per hour (with optional Vent Kit installed) at 300% Duty Cycle for 30 seconds