abb inverters replace soft start units

Our engineers returned to Skye this week to complete the installation of two ABB ACQ580 water drives.

Due to the high number of start-ups required, the soft starts (on a waste water treatment works) were being replaced by variable speed drives.

The versatility afforded by using VSDs on the system means that both money and energy will be saved. And the end result for our customer? Greater control, less damage to mechanical and electrical set ups and a future-proofed system. 

Considering replacing your current soft starts with a variable speed drive solution? Contact our engineers or read more about why an inverter might be a suitable replacement for a sort start.


  • Applications that require speed and torque control only during start up
  • You're looking for convenience and simplicity of design and operation
  • You don't need to vary the speed of your operation, just create a smooth start
  • No complicated programming is required 
  • Space is an issue (soft starters tend to be smaller compared to a comparably sized VSD)


  • You need to have complete control of your motor - at all times
  • You have an issue with starting torque - a VSD will generate much greater starting torque than a soft start.
  • Energy saving is important - a drive can reduce power when not required (this saved energy will ultimately pay for the cost price of the drive)
  • Diagnostics and system protection are required - VSDs come with diagnostics and can be used in place of PLCs
  • You have transients in a pipework system which you need to control