Soft Starter System

Variable speed drive system for Downstream industries

For industrial applications where the production processes require very high-power equipment–typically like PTA, petrochemical, air separation or carbon capture, starting the machine directly on line or with a classic starter (auto transformer, variable voltage drive, etc.) could result in serious damages to the whole installation. This is where a variable speed drive is needed, to allow the start with an inrush current not exceeding the nominal motor current.

Power Conversion offers a soft starter variable speed drive system based on a combination of Voltage Source Inverter (VSI) or Load Commuted Inverter (LCI) and an electrical motor.

Soft Starter system


● Synchronous or induction technology

● 50 or 60 Hz according to the grid frequency

● Capability to start several motors with a single soft starter


● Up to 60 MW

● Up to and 11 kV output motor voltage


● LCI + synchronous motor

● DFE VSI + either sync or induction motor

We propose the complete system engineering including grid harmonics study and mechanical shaft analysis


  • Smooth starting of the compressor
  • No inrush current on the grid
  • No mechanical stress on the motor
  • Full flexibility available in terms of power demand
  • Very fast starting and high operating reliability and availability: starting time <1 min
  • Emission-free solutions/Fit with environmental restrictions
  • Minimum maintenance period over life cycle
  • Low operation maintenance cost
  • Suitable for most areas, incl. with limited power availability
  • Real-time simulation for efficient commissioning


Power Conversion contributes to the development of the first Purified Terephthalic Acid (PTA) facility in Turkey