the characteristics of the electromagnet

the characteristics of the electromagnet
The nature of its coil current can be divided into AC DC solenoid and electromagnet; according to different uses can be divided into traction magnet, brake magnet, lifting magnet and other types of special electromagnet. Traction magnet mainly used for automatic control apparatus for pulling or repulsive mechanical devices, in order to achieve the purpose of automatic control or remote; brake solenoid is used to operate the brakes, the brake in order to complete the task electromagnet; electromagnetic lifting Iron is used for lifting, carrying heavy loads ferromagnetic electromagnet. 3. Electromagnet different depending on the power supply, the following three: ① AC solenoids. AC solenoid valve voltage is generally used AC 220V, electrical wiring configuration is simple. AC solenoid actuation force is large, the commutation time is short. But reversing the impact of large, Drawer magnets working temperature rise (housing with cooling ribs); when the spool is jammed, the electromagnet easy to burn out due to excessive current, less reliable, so the switching frequency must not exceed 30 times / min short-lived. ② DC solenoids. DC 24V DC voltage solenoid general use, requiring dedicated DC power supply. The advantage is that the core will not get stuck and burn (its cylindrical shell without cooling ribs), small, reliable, allows switching frequency is 120 times / min, reversing the impact of small, long service life. But starting force smaller than AC electromagnet. ③ This integer electromagnet. The integer represents the local AC rectifier. The electromagnet itself with half-wave rectifier, AC power can be directly used at the same time, a DC electromagnet structure and properties. 1, first power supply design, namely the voltage across the coil. DC power supply is recommended, because the DC current can guarantee stable suction times, no alternating. Magnetic attractive force between the small of your design, you can choose 5-12V DC power supply (voltage greater the reaction faster). 2, winding group of materials selection, if the design requires winding group of light weight, you can choose enamelled wire. Generally, the selection enamelled copper wire, because the low resistance of copper. 3, consider the group of heating wire, there is a resistance of the winding group, the heating power P = U * U / R (U is the supply voltage). 4, the selection of a suitable conductor cross-sectional area as the winding pack. 5, the magnetic force Fα magnetic induction B, the BαI * N (product of current and the number of turns), and I = U / R, and RαN. (Complex bars, simplify) the specific formula: B = u * I * N / 2; R = ρ * L / S = ρ * π * D * N / S; (u is the magnetic permeability of the wheels, ρ the wire resistivity, S is the cross sectional area of ​​the wire, D is the average diameter of the coil ≈ 32mm, N ≈ 0.85 * (20-12) * 33.5 / S, L is the conductor length. Notes: S units of mm; ρ The unit is ohm mm) are: B ≈ 0.59 * u * S / ρ (as long as it can be seen winding a certain area, B, and N contents) to see coil heating power: P = U * U / Rα (S ^ 2 ); therefore try to take a small conductor cross-section S, but S is too small will lead to changes in magnetic force is slow.