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Lifting_electromagnet

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					Lifting_electromagnet.xls
By Alex Slocum, Last modified 6/22/03 by Alex Slocum
To determine magnet properties to lift a mass, remember, like current in a
series circuit, the flux in a series magnetic circuit is constant.
Enters numbers in BOLD, Results in RED
Mass of object to lift, M (kg)                                              0.5
Force required to lift object, F (N)                                        4.9
Total required Magnetomotive force, MMFtotal (At)                          37.6
  Available current, Iavail (amps)                                          0.5
  Minimum number of required turns                                         75.2
Air gap
  Area of first pole, Ap_1 (mm^2)                                           600                                         1.8
  Length of first air gap, Lag1 (mm)                                        0.1                                         1.7
  Area of second pole, Ap_2 (mm^2)                                          600
  Length of second air gap, Lag2 (mm)                                       0.1                                         1.6
  Required magnetic flux density to lift object, Breq (Tesla)            0.101                                          1.5




                                                                                  Magnetic flux density B (T = tesla)
  Magnetic field intensity Fm @Breq, MMFag (At)                            16.1
Required magnetic circuit flux, phi (Wb)                            6.08E-05                                            1.4
Lifting magnet                                                     sheet steel                                          1.3
  Section 1
     Magnetic circuit path length, L_1 (mm)                                  25                                         1.2
     Magnetic circuit path area, A_1 (mm^2)                                 600                                         1.1
     Flux density, B_1 (Tesla)                                           0.101
     From B-H curve, magnetic field intensity, H_1 (At/m)                    50                                         1.0
     Magnetomotive force (MMF), MMF_1 (At)                                 1.25
  Section 2
                                                                                                                        0.9
     Magnetic circuit path length, L_2 (mm)                                  60                                         0.8
     Magnetic circuit path area, A_2 (mm^2)                                 600
     Flux density, B_2 (Tesla)                                           0.101
                                                                                                                        0.7
     From B-H curve, magnetic field intensity, H_2 (At/m)                    50                                         0.6
     Magnetomotive force (MMF), MMF_2 (At)                                    3
  Section 3
                                                                                                                        0.5
     Magnetic circuit path length, L_3 (mm)                                  25                                         0.4
     Magnetic circuit path area, A_3 (mm^2)                                 600
     Flux density, B_3 (Tesla)                                           0.101
                                                                                                                        0.3
     From B-H curve, magnetic field intensity, H_3 (At/m)                    50                                         0.2
     Magnetomotive force (MMF), MMF_3 (At)                                 1.25
Object being lifted                                                  cast iron
                                                                                                                        0.1
  Magnetic circuit path length, Lobl (mm)                                    80                                         0.0
  Magnetic circuit path area, Aobl (mm^2)                                  600
                                                                                                                              0   400   800   1200   1600
  Flux density, Bobl (Tesla)                                            0.101
  From B-H curve, magnetic field intensity @Breq, Hobl (At/m)               200
  Magnetomotive force (MMF), MMFobl (At)                                     16
                                                                                                                                          Magnetic f
Permeativity of free space, mu0 (H/m)                               1.26E-06

                                                                   4.7279E-05
Magnetomotoive force (MMF) (number of Ampere-turns) is required to force the needed flux
through the reluctances in the magnetic circuit:




                                             1.8
                                             1.7
                                             1.6
                                             1.5
       Magnetic flux density B (T = tesla)




                                             1.4
                                             1.3
                                             1.2                                                                    Mild steel
                                             1.1                                                                    Cast steel
                                             1.0                                                                    Cast iron
                                             0.9
                                             0.8
                                             0.7
                                             0.6
                                             0.5
                                             0.4
                                             0.3
                                             0.2
                                             0.1
                                             0.0
                                                   0   400   800   1200   1600   2000   2400   2800   3200   3600   4000   440

                                                               Magnetic field intensity H (At/m = ampere-turn
           Mild steel sheet
           Cast steel
           Cast iron




0   3600    4000   4400   4800   5200   5600   6000

m = ampere-turns/meter)

				
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posted:11/28/2011
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