Eddy current dynamometer working principle

The eddy current dynamometer measures the torque and power of the prime mover (motor or engine). The rotor rotates with the help of the prime mover shaft and the voltage is applied to the coil or stator housing. Since such magnetic flux is generated and the rotor cuts off these magnetic fluxes, the eddy current opposite to the change in magnetic flux is generated in the rotor.

Therefore, the rotor obtains a reverse force and attempts to reduce the rotational speed of the rotor. But the torque provided by the prime mover keeps the speed. This torque is measured by a sensor at the end of the arm on the dynamometer.

POWERLINK GW series eddy current dynamometer, as a kind of load, is mainly used to measure the various characteristics of dynamic mechanical test equipment. The eddy current dynamometer is applicable to the performance test of internal combustion engine, medium and small power motor, automobile transmission parts, gas turbine, water turbine, engineering machinery, forestry, mining and oil drilling. It can also be used as power absorbing device of other power equipment.


Eddy current dynamometer


Main features of eddy current dynamometer


  • Having the advantages of simple structure, convenient operation and maintenance
  • Having large braking torque, high precision, stable operation
  • Small rotational inertia and fast dynamic response
  • With monitoring and control system can realize the automatic operation


Major technical specifications


  • Cooling medium: Clean and fresh water, free of impurities and debris
  • Cooling water pressure: 0.2 ~ 0.4Mpa
  • Dynamometer water outlet temperature: Less than 50℃
  • Direction of operation: Left-handed or right-handed, continuous work
  • Torque measurement accuracy: ±4% FS (GW6 to GW100), ±0.2% FS (GW160 to GW2000)
  • Speed measurement accuracy: ±1rpm
  • Torque measurement sensor: Tension-compression force transducer
  • Speed measurement sensor: 60 pulse magnetic-type speed sensor


Gasoline, diesel, CNG or LPG engine endurance test with eddy current dynamometer

Eddy current dynamometer


Electric or hybrid vehicle motor endurance test with eddy current dynamometer

Eddy current dynamometer


Gearbox, torque converter or transmission test with eddy current dynamometer

Eddy current dynamometer


Containerized diesel or gasoline engine test bench with eddy current dynamometer

Eddy current dynamometer


Work principle of eddy current dynamometer


Eddy current dynamometer consists of brake, measuring force and speed measuring device, etc. The brake regulates the load of the prime mover, and at the same time converts the absorbed prime mover power into heat, which is taken away by the water.

The torque measurement of eddy current dynamometer is according to the principle of same amount of applied torque and reaction torque with opposite direction. So the torque can be measured by the dynamometer rotating torque (i.e. brake housing counter-torque) to indicate.


Major technical parameters of eddy current dynamometer


ModelRated power (kW)Rated torque (Nm)Max. speed (rpm)



Structural main components


  • Rotating section (sensing body)
  • Swing section (armature and excitation section)
  • Force measurement section
  • Calibration components


It can be seen from the eddy current dynamometer structural diagram that the shape of the inductor is like a spur gear and the eddy current is generated on the hole wall of the magnetic eddy current ring. After connecting direct current through excitation winding, the excitation winding generates a closed magnetic flux.

When the inductor is rotated by the prime mover, the air gap flux density changes periodically with the rotation of the inductor. The eddy current potential will be generated on the surface of eddy current ring hole and certain depth, then the eddy current will be formed.

The magnetic field interacts with the air-gap magnetic field to produce the braking torque. The torque passes through the outer ring and force arm to the force measurement device. The force sensor will transmit the force size as the electrical signal output so as to achieve the purpose of torque measurement.

Speed measurement uses non-contact magnetic-type speed sensor. The speed signal transmitted as electrical signals.


Parameter selection and curve download



Application description download