Tramp Iron Removal

Rectangular core electromagnets work by winding electrically conducting material such as wire or strip on to a high permeability rectangular steel core. When energised, this electromagnet creates magnetic flux which returns to the core because of carbon steel side poles and a backbar. This effectively creates a magnetic circuit with a width as wide as the rectangular enclosure, which is ideal for extracting ferrous metal which comes into contact with the magnetic field and are then attracted to the magnet face. The magnet can be suspended horizontally, such as over a conveyor or it can be suspended at steep incline angles of 65° to 90° at the discharge end of feeders and screens to attract ferrous material. Once ferrous metal is collected at the magnet face, the magnet must be moved out of position and de-energised for material release.

POWERSMART “Self-Air Cooled” magnets use “Anodised Aluminium Foil” as the coil conductor winding material. By employing this material, as well as the “direct on to core” disc winding method it is possible to have an electromagnet that uses no oil or force cooling mechanism like fans and is naturally self-air cooled with a fully welded enclosure.

Anodised aluminium strip is a conductor material with a 5µm thick ceramic oxide (anodised) layer which forms the electrical insulation of the conductor material, no additional covering such as Nomex or glass fire yarn is required.

The efficiency of this type of winding also enables a drastic power consumption savings versus equivalent oil/fan types (Energy Efficient); there is also no difference in magnetic performance comparative to equivalent oil/fan cooled types.

The reduced power consumption is achieved by designing the DC magnet coil winding for as many turns as possible in a certain coil radial depth coupled with current/amperage input, as opposed to a design with few turns and many amps resulting in more watt loss/heat which requires cooling oil. The reduced amperage fed into the coil means there is less resistive heat loss (Joule Heating) and power consumption (kW). The ANS range of magnets use almost half the kW power consumption of equivalent oil filled magnets for the same magnetic performance. The coil resistive watts loss is not a measure of the magnetic field flux density (gauss). The flux density depends on the core dimensions and the coil ampere-turns. A coil can have a few turns and many amps (high watts), or many turns and few amps (low watts).

The magnets are then naturally cooled by winding the coil directly “on to the core” and letting the core act as a heat sink to conduct the heat to the enclosure. The heat is then radiated out into the atmosphere via the magnet top plate (back bar). This magnet cooling in large electromagnets can only be achieved using anodised aluminium strip which allows for a coil winding fill factor of 99%, with a wire wound coil the air spaces between the wire wouldn’t allow for efficient heat transfer.