The lifting force of an electro magnet is determined by three factors which are:
- The size (and geometry) of the ferrous core (the larger, the stronger)
- The quantity of turns that constitute the winding (the more, the stronger)
- The quantity of direct current (Amps, Idc) passing through the winding (the more, the stronger)
Once an electro magnet is designed and built, the first two elements (size and turns) are set while the third one (current) can vary based on direct voltage (Vdc) setting and winding temperature that impacts the electrical resistance (R) of the winding conductor (Vdc= R x Idc). Electro magnets generate heat (Joule effect) when energized and the hotter the magnet winding, the more the current decreases.
The four elements that impact the internal temperature of an electro magnets are:
- Temperature of material to be lifted (in case of a hot application)
- Duty cycle
- Current density of the winding conductor
- Type of winding conductor.
The first two elements (material temperature and duty cycle) are specific to every application and situation while current density and the type of magnet winding conductor are decided by magnet designer.
In order to optimize heat dissipation, magnet force and magnet life time, the SGM electro magnets are designed with very conservative electrical density for their winding and, as a standard, their windings are of anodized aluminum strip.