Electromagnets & Power Supplies (Electromagnet Controls)
- Custom Electromagnet Power Supplies
- Bipolar (Parallel Pole) Electro Magnets
- Round Electro Magnets
- Rectangular Electro Magnets
Dura offers a variety of standard electromagnets for immediate shipment, or we can design a custom electro magnet unit that is application specific. Our stock product offering is available in a variety of shapes and sizes, and operational voltages. All stock electromagnets are 100% duty cycle rated and designed to limit the internal heat level relative to the ambient temperature.
Standard Electromagnets:
| Shapes: | Operational Voltages: |
| Round | 12 VDC |
| Square / Rectangular | 24 VDC |
| Parallel Pole / Bipolar | 110 VDC |
| *120 VAC (Requires AC plug and integrated rectifier) |
ETO (Engineered to Order) Electro Magnet:
Application specific electromagnets can be tailored to meet a variety of custom design criteria. Below are the common requirements which require a variation of a standard electromagnet or a custom magnet design.
Physical - Volume, Mass, Dimensional Constraints or Mounting Method
Operational Voltage - Magnitude and Frequency
Duty Cycle - Continuous or Intermittent Duty
Environmental Concerns - Stainless Steel or Special Coating Requirements
Electro Magnet Controllers and Power Supplies:
All electromagnets require an applied voltage in order to generate a magnetic field. Typically the applied voltage is Direct Current (DC), but in some cases Alternating Current (AC) can be used. These cases require an integrated rectifier in the electromagnet's housing or AC plug. When employing a single electromagnet the AC plug option is more cost effective than purchasing a stand alone controller or power supply. AC voltage can also be used in very specialized electromagnets where eddy current losses are reduced by the use of housing laminations. This is a very special case and typically limited to large production quantities of electro magnets.
A controller / power supply is employed when multiple electromagnets are used in an array, PLC control is required, a "reverse pulse" is required for a positive release, or the electromagnets are small and lower voltages are required.
Controllers are available in a variety of input and output voltages, power levels, and control options. Dura's automatic power supplies employ a "current reverse" pulse for positive release and can be controlled by a continuity state change on integrated terminals.
Theory of Electro Magnet Operation:
An electromagnet consists of two major components, the coil / solenoid and the housing. The housing is an integral part of the electro magnet circuit and not only provides the mechanical structure, but also imparts additional magnetic flux and acts as a conduit for that flux.
Electro Magnet Coil: As in permanent magnets, an electromagnet's magnetic field is a result of a moving charge. In a permanent magnet the moving charge is an un-paired electron spin in the valance shell, but in an electromagnet the moving charge is the conduction electrons circulating in the coil. The electrons circulate because of the applied voltage and the resulting current density (j) X Number or Turns (n) is proportional to the established magnetic field.
The product above is proportional because the equation for an ideal coil / solenoid (Amp*Turn/ Unit Length) is usually only a first order approximation when the coil's axial length is much shorter than their diameter (Length / Diameter < 1). For most commercially available electromagnets this ratio exists.
Electro Magnet Housing / Yoke:
The established magnetic field from the coil is relatively small, but it is multiplied by magnetic induction in the steel housing. Most of the magnetic field from the electromagnet is from the magnetic induction and the resulting field resides close to the working face of the magnet and does not project very far. This is why electromagnets work very poorly through gaps and are intended to be used in direct contact.
Electro Magnet Pros: Can be turned off
No moving parts
Variable strength options
Electro Magnet Cons: Require applied power
Poor field projection
Low power density (Lower power per unit volume)
Fail in the OFF condition