Eaton DS7 Series Soft Start Controller – Product Spotlight

Eaton’s DS7 Series Soft Start Controllers are reduced voltage solid-state soft start controllers with a small footprint. These start controllers are multi-functional, easy to install and easy to commission. These controllers are purpose-built to control the acceleration and deceleration of three-phase motors with ability to adjust initial torque and ramp up and down time.

These controllers are available for current ranges from 4 to 32 A in four frame sizes.



Eaton’s DS7 Series Soft Start Controllers, available at! Pictured is the DS7340SX055N0-N model with 24 AC/DC control.


With its small size, the DS7 start controller can easily fit in place of existing soft starters, wye-delta starters or across-the-line NEMA and IEC starters. The small footprint makes the controller and ideal solution to upgrade existing systems.

Using silicon controlled rectifiers (SCRs) to ramp the voltage to the motor, the DS7 soft start controller provides smooth acceleration and deceleration of the load. After the motor is started, the internal run bypass relay closes, resulting in the motor running directly across-the-line.

Internal run bypass drastically reduces the heat generated compared to starters without bypass. This feature extends the lifetime of connected components.

It is worth noting that – unlike Eaton’s larger soft starters, the S801+ and S811+ – these controllers require external overload protection relays or circuit breakers to protect the system. This controller is able to monitor a few system characteristics to protect the device:

  • Mains connection – mains connection is monitored for phase loss and/or undervoltage during ramp up
  • Motor connection – motor connection is monitored for an open condition during the ramp
  • SCR faults – SCR performance is monitored during the ramp cycle for proper operation
  • Heat sink over/undertemp – Sensors monitor the temperature of the device, tripping the soft starter to protect it from extreme temperatures that cripple performance and damage the controller

For more information about Eaton’s DS7 Series Soft Start Controllers, contact our experts today!


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