Hydraulic dynamometers are used to measure the force, torque, and power that is produced by different types of engines, motors and other varieties of rotating movers. Power is capable of being calculated by measuring rotational speed.

Hydraulic dynamometer: It works on the principle of dissipating heat in the fluid friction rather than dry friction. Its construction is similar to that of the fluid wheel and it consists of an impeller coupled to the output shaft of the engine. The impeller rotates inside a casing filled with fluid.

Hydraulic Dynamometers Hydraulic dynamometers are used to measure the power of an engine by using a cell filled with liquid to increase its load.

Fluid dynamometers work like water turbines: as you spin their axles, you turn a paddle inside a drum filled with water (or thick oil). That provides the resistance and load, and the power produced by an engine, motor, or other machine under test is dissipated by the water or oil heating up as the paddle turns.

Absorption dynamometers can be equipped with two types of control systems to provide different main test types.

• Constant force.
• Constant speed.
• Types of absorption units.
• Eddy current type absorber.
• Powder dynamometer.
• Hysteresis dynamometers.
• Electric motor/generator dynamometer.
• Fan brake.

A dynamometer, or “dyno” for short, is a device for measuring force, moment of force (torque), or power. A dynamometer can also be used to determine the torque and power required to operate a driven machine such as a pump. In that case, a motoring or driving dynamometer is used.

They are used in a variety of industries from laboratory science to manufacturing. Dynamometers are extensively used in the automotive industry to determine horsepower, max power absorption, and max rotary speed. Due to wear, temperature changes, or corrosion, sensors tend to drift away from the original calibration.

An isokinetic dynamometer is a device used within sports and exercise science as well as clinical testing environments that is used to evaluate joint torque. Isokinetic dynamometers are able to test the strength (torque) and power of different muscle groups.

An eddy current dynamometer works on the principle of Faradays’ Law of electromagnetic induction. As per the law, whenever there is a relative displacement between a set of conductors and a magnetic field, an emf is induced on the set of the conductor. This emf is called is dynamically induced emf.

The advantages of eddy current testing are: Sensitivity to surface defects. Able to detect defects of 0.5mm in length under favourable conditions. Can detect through several layers.

Eddy currents are swirls of electric currents induced within conductors by a changing magnetic field within the conductor (self-inductance). Eddy current works on the principle of Faraday’s law of induction. The Eddy Current Principle works as the Self-inductance.

Eddy current has an efficiency of 100% which means it gives all the energy to do the work. Thus, Eddy current is not used in an electric heater. Hence, the correct answer is option D i.e. electric heater.

Eddy current allows analysts to inspect materials on a surface and near-surface level. The best eddy current instruments can detect cracks for complex inspections like tubing via multiple frequencies and dual options, and can pick up developing cracks as small as 0.1 mm or less in depth.

Which of the following will not increase the size and effect of eddy current? Stronger magnetic field, thicker material and low resistivity material will increase the size and effect of eddy current whereas thinner material will reduce the effect of eddy currents.

laminating core

They can be created when a conductor is moving through a magnetic field, or when the magnetic field surrounding a stationary conductor is varying i.e. anything which results in the conductor experiencing a change in the intensity or direction of a magnetic field can produce eddy currents.

The eddy current loss occurs because of the interaction of magnetic field and conductor. The hysteresis loss occurs because of the reversal of the magnetism. The eddy current loss is minimised by using the thin core of lamination. The silicon steel material is used for minimising the hysteresis loss.

Electromagnetic damping is one of the most interesting damping techniques, which uses electromagnetically induced currents to slow down the motion of a moving object without any physical contact with the moving object. Thus the eddy currents swirl in a plane perpendicular to the magnetic field.

The electromagnetic damping force is proportional to the induced eddy current, strength of the magnetic field and the speed of the object. Which implies that faster the object moves, greater will be the damping and slower the motion of object lower will be damping which will result in the smooth stopping of the object.

Damping

• Vibration.
• Viscous damping.
• Damped vibration.
• Hysteresis damping.
• Landau damping.
• Magnetic damping.
• Radiation damping.
• Velocity-squared damping.