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Electromagnets

An electromagnet uses flow of electric current to produce magnetic field. The magnetic field disappears when the current is turned off. The main advantage an electromagnet has over a permanent magnet is its adjustability. The magnetic field can be adjusted over a wide range and the structure of the magnet can be designed for easy manipulation to accommodate different air gap needs. The main draw back of electromagnet is the power consumption due to copper losses and, in the case of AC electromagnet, iron losses. If the generated heat due to losses is excessive, a forced means of cooling may be required to remove the excess heat and assure consistent performance. Two common methods of cooling electromagnets are forced convection and water-cooling. If such thermal relief is necessary, additional space in the final application should be provided to implement the necessary hardware.

A DC (direct current) electromagnet often involves ferromagnetic core and yoke materials to maximize the magnetic field. At Dexter, we utilize advanced numerical analysis techniques to offer optimized design for specific applications. Among our standard offerings, we have patented alignment electromagnet frame for generating highly uniform external field. We also provide adjustable air gap, water cooled high power high uniformity electromagnet.

Dexter_Alignment_Electromagnet Dexter_Electromagnet_2

Alignment Magnet - Electromagnet

Electromagnet

In AC (alternating current) electromagnet, the constantly changing magnetic field causes losses in the magnetic cores in the form of eddy current loss and hysteresis loss. Both losses increase along with increasing frequency. To minimize these losses, the core is often high resistive or laminated material such as soft ferrite, powdered iron; SiFe laminates or amorphous materials. Dexter offers soft ferrite; powdered iron; laminates and amorphous cores from major producers. Dexter's engineering staff can be consulted to help decide upon the most appropriate core material for your AC electromagnet applications.

We have experience designing:

  • alignment DC
  • alignment electromagnet for highly uniform external field
  • water cooled high power, high uniformity electromagnet
  • capacitor discharge electromagnet for high intensity, high uniformity field

When working with our engineering group, you might be asked:

  1. What is the available space?
    a. desired size of the electromagnet
    b. the air gap

2. What are the magnetic field requirements?
     a. magnitude
     b. uniformity
     c. the magnetic field region of interest
     d. duty cycle at peak power

3. What are your power supply specifications?
     a. the range for current and voltage
     b. computer or manual control.

For DC electromagnet, we often use low carbon steel for the core and yoke because of its low cost and high saturation magnetization. CoFe alloy has the highest saturation magnetization among ferromagnetic materials and can considered when tight space or low weight is required.

For AC electromagnet, we often use high resistance, low coercivity material for the core and yoke such as soft ferrite and powered iron. We also use laminated cores such as laminated SiFe and amorphous material for their low eddy current loss.

Once we have the requirements as listed in the “Help Me Design” section, we will start our design process with numerical simulation and other techniques. The design cycle can be in a matter of a couple of weeks. The prototyping can be a few weeks to a couple of months depending upon the complexity of the system.