Contents
What is eddy current damping?
As an alternative to the use of traditional vibration suppression devices, a novel eddy current damper (ECD) is proposed to suppress mechanical system vibration. The design utilises the relative motion between a permanent magnet and conductor to create a resistive force.
What are the effects of eddy current?
Thus, eddy currents occur in the stator and rotor cores of electric motors and generators, in transformers, metallic recording heads (used in magnetic recording), and the like. These eddy currents can produce undesirable effects such as power loss, heating, and—in magnetic recording—degradation in performance.
How much does an eddy current cost?
The price for a small rare earth eddy current separator for a MRF can start at $35,000, while a larger separator for more severe-duty applications can cost up to $160,000.
How eddy current is used as damping?
When a conductive material is subjected to a time-varying magnetic flux, eddy currents are generated in the conductor. As the eddy currents are dissipated, energy is removed from the system, thus producing a damp- ing effect.
What is the principle of electromagnetic damping?
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.
What is eddy current used for?
Eddy current testing is a non-destructive testing (NDT) inspection method used for a variety of purposes, including for flaw detection, material and coating thickness measurements, material identification and establishing the heat treatment condition of certain materials.
What are the advantages & disadvantages of eddy current inspection?
What are the advantages and disadvantages of eddy current testing?
- Sensitivity to surface defects.
- Can detect through several layers.
- Can detect through surface coatings.
- Accurate conductivity measurements.
- Can be automated.
- Little pre-cleaning required.
- Portability.
- The disadvantages of eddy current testing are:
How does eddy current NDT work?
In an eddy current probe, an alternating current flows through a wire coil and generates an oscillating magnetic field. The eddy current instrument plots changes in the impedance amplitude and phase angle, which can be used by a trained operator to identify changes in the test piece.
How does electromagnetic damping work?
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.
Eddy currents can produce significant drag, called magnetic damping, on the motion involved. Consider the apparatus shown in Figure 23.7. 1, which swings a pendulum bob between the poles of a strong magnet. (This is another favorite physics lab activity.)
How is the eddy current set up in the field?
As it enters from the left, flux increases, and so an eddy current is set up (Faraday’s law) in the counterclockwise direction (Lenz’s law), as shown. Only the right-hand side of the current loop is in the field, so that there is an unopposed force on it to the left (RHR-1).
How does a metal plate affect the eddy current?
When the metal plate is completely inside the field, there is no eddy current if the field is uniform, since the flux remains constant in this region. But when the plate leaves the field on the right, flux decreases, causing an eddy current in the clockwise direction that, again, experiences a force to the left, further slowing the motion.
As discussed in Motional Emf, motional emf is induced when a conductor moves in a magnetic field or when a magnetic field moves relative to a conductor. If motional emf can cause a current loop in the conductor, we refer to that current as an eddy current. Eddy currents can produce significant drag, called magnetic damping, on the motion involved.