Tandem Dynamometer - For Motor Testing

Tandem dynamometer also called as hybrid dynamometer, is combination of powder dynamometer & eddy current dynamometer. Tandem dynamometers are used for testing prime mover right from zero rpm to extended speed range.
Powder dynamometers, as their name suggests, contain magnetic powder in dynamometer. The electrical current passing through the coil generates a magnetic field, which changes the property of the powder from free flowing condition at no excitation, to solid rock condition at full excitation. Thus producing a smooth braking torque through friction between rotor and stator – proportional to excitation.
Eddy current dynamometer, is simple dynamic load system for accurate testing of all type of electric motors, air motors, hydraulic motors, engines and other rotating machinery's. Eddy current dynamometer provides the ideal solution for accurate analysis of power, torque, speed, fuel and lubrication consumption and quick pass fail testing of all type of electric motors, engines, gears and other rotating machineries.
In eddy current dynamometers rated torque is developed at approximately 15% to 25% of maximum speed capability depending on models.advantage of powder dynamometer is that it controls torque right from zero rpm but has poor heat dissipation capacity (due to higher speed), whereas eddy current dynamometer operating range is 300 rpm onwards to 18000 30000rpm, but below 300 rpm it doesn’t produce rated braking torque.hence, to apply torque loading from zero rpm to full speed - tandem dynamometer – at lower speed powder dynamometer is in operation, whereas at higher speeds eddy current dynamometer are in use. Powder dynamometer & eddy current dynamometer are constructed in line, has one output shaft, to be coupled to unit under test.