Products - Dynamometers - AC Dynamometers

Froude AC Dynamometer

The Froude AC dynamometer has been specifically designed for the testing of gasoline and diesel engines in R & D and Quality Audit applications.  

Low inertia AC motor with standard speed ranges from 3,500 rpm to 10,000 rpm

Standard torque hub measurement accuracy is +/-0.2% of the full rated torque of the dynamometer

Speed is measured to an accuracy of +/- 1 rpm

Model Max Speed (RPM) Torque Nm (lb.ft) Power
kW (BHP)
Power (Motor)
kW (BHP)
AC140 10,000 276 (205) 140 (188) 129 (173)
AC250 10,000 460 (340) 250 (335) 235 (315)
AC360 10,000 720 (535) 360 (483) 340 (456)
AC400 4,000 1,900 (1405) 400 (536) 400 (536)
AC460 9,000 973 (720) 460 (617) 440 (590)
AC570 4,000 3200 (2360) 570 (764) 570 (764)
AC690 3,500 4500 (3320) 690 (925) 690 (925)


The AC dynamometer is constructed using a low inertia AC motor especially designed for engine test applications mounted on a substantial fabricated baseframe. On foot mounted versions torque is measured using an in-line torque hub. For trunnion mounted machines a precision strain gauge load cell is used. As an option both versions can include an integrated jackshaft that provides additional overhung load capacity for the engine drive shaft. 

Heat generated within the dynamometer is dissipated using the integral cooling fan. The AC dynamometer is supplied with a 4-quadrant flux vector AC inverter. This state-of-the-art technology incorporates high speed IGBT (Insulated Gate Bipolar Transistor) and sophisticated control algorithms to provide excellent transient response and steady state control. The drive incorporates a special input stage which operates at near unity power factor, minimises supply current harmonics and in re-generation mode frequency matches to the mains supply. The AC dynamometer and inverter drive unit are designed for use with Froude's range of Texcel control and data acquisition systems.


The Froude AC dynamometer is designed to meet the requirements of high performance motoring, absorbing engine development, and Quality Assurance testing.

Available in trunnion and foot mounted configurations and with a range of additional options including jackshafts and hi-dynamic performance, these machines have been specifically designed to provide the performance and durability required for today's testing environment.


  • Standard range of AC dynamometers consists of machines up to 1,055 kW
  • Standard torque hub measurement accuracy is + 0.2% of the full rated torque of the dynamometer
  • Speed is measured using an encoder providing an accuracy of + 1 rpm
  • Transient response typically 9000 rpm/sec
  • Operating voltage 380/416V 50Hz or 460V 60Hz

Visit our Global Sales Page to inquire about Froude Equipment, or fill out the contact form below.

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  • Non-standard sizes are available on request
  • Integrated jackshaft to increase the overhung load capacity of the dynamometer
  • Hi-dynamic performance
  • Deadweight calibration equipment
  • Control and Data Acquisition systems
  • Throttle actuators/In-cell ancillaries
  • Engine support stands

Customer Service

  • Facilities planning and installation services
  • Comprehensive in-house and/or on-site training courses
  • Tailored preventative maintenance contracts
  • On-line diagnostics and support via modem or VPN
  • Technical Support

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