Eddy Current Dynamometer

Eddy Current Dynamometer

It consists of a stator on which are fitted a number of electromagnets and a rotor disc made of copper or steel and coupled to the output shaft of the engine. When the rotor rotates eddy currents are produced in the stator due to magnetic flux set up by the passage of field current in the electromagnets. These eddy currents are dissipated in producing heat so that this type of dynamometer also requires some cooling arrangement. The torque is measured exactly as in other types of absorption dynamometers, i.e. with the help of a moment arm. The load is controlled by regulating the current in the electromagnets.

Eddy current dynamometer
Eddy current dynamometer

The following are the main advantages of eddy current dynamometer:

(a) High brake power per unit weight of dynamometer.

(b) They offer the highest ratio of constant power speed range (up to 5 : 1).

(c) Level of field excitation is below 1% of total power being handled by dynamometer, thus, easy to control and programme.

(d) Development of eddy current is smooth hence the torque is also smooth and continuous under all conditions.

(e) Relatively higher torque under low speed conditions.

(f) It has no intricate rotating parts except shaft bearing.

(g) No natural limit to size-either small or large.

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