ISA hd


ISA hd
Rated operational current
60 to 2,500 A
Main voltage
2.3kV – 13.8kV

The ISA HD is a powerful medium-voltage soft starter designed for all AC induction motors in medium-voltage industrial applications.

Its advanced motor control technology ensures smooth acceleration and deceleration, greatly reducing the impact of high inrush currents and mechanical torque shocks.

With its flexible design, enhanced motor protection, and excellent global reputation, the ISA HD stands as the top choice for starting solutions in medium-voltage applications, even in the most challenging environments.


  • Up to 50°C ambient temperature
  • Enhanced motor protection package
  • IP 31 as standard, up to IP54 optional
  • Wide 45 – 65Hz range auto-frequency tracking
  • Automatic triggering of the firing angle (designed for marine, offshore and generator operating under continuous frequency variation)
  • Innovative low voltage test – testing of complete function
  • Nominal voltage test – option
  • Synchronous motor starting, utilizing unique module
  • Compact 2-phase control configuration (optional)
  • Fault recorder – real-time clock included
  • Data Logger – An integrated current and voltage wave recorder with sampling rate of up to 50kHz and advanced graphic software interface for remote waveform monitoring (optional)
  • Multi-language interface
  • User friendly configuration


  • Configurable starting & stopping characteristics
  • Enhanced motor protection package
  • User friendly setup and operation
  • Multi-soft start and multi-soft stop
  • Unique modular synchronous motor starting
  • Advanced Electronic Current & Potential Transformer
  • Partial Discharge test according to EN50178/625.1
  • Direct Power Factor Capacitor connection
  • Unique Pump start/stop curves including special torque curve


  • 2-phase control
  • Modbus
  • Profibus
  • DeviceNet
  • Insulation test
  • Analog output
  • Multi motor soft-start/stop
  • Data Logger
  • Marine inspections and certificates

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