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)
GW662512,000
GW10105012,000
GW16167012,000
GW252512011,000
GW404016010,000
GW63632509,000
GW1001004008,500
GW1601606008,000
GW2002008007,500
GW2502501,1007,000
GW3003001,1006,500
GW3203201,5006,000
GW4004002,2005,200
GW5005002,8005,000
GW6306303,6004,500
GW8008005,0004,000
GW10001,0007,0004,000
GW12001,2009,0003,800
GW16001,60011,0003,500
GW20002,00014,0003,200

 

 

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.

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Parameter selection and curve download

 

 

Application description download