The magnetic Reynolds number , or the dimensionless frequency, equal to Here is the angular velocity; is the specific electrical conductivity of the rotor; is the pole division ; is a coefficient which considers the decrease in electrical conductivity due to the finite length of the rotor, including reduction due to the resistance of its projections. From (6.2), (6.3) and (6.7) it is obvious that at small velocities of rotation he brake momentum is virtually proportional to . At a certain velocity called the critical velocity, the momentum is maximal. It should be noted that saturation of the characteristic is useful, since it protects the shock absorber from overload at large deformation velocities. The initial slope of the momentum of the characteristic is defined by the f ormula The maximum momentum of a nonsalient pole brake is attained at . and for salient pole brakes, at. The value is also close to 1. Then the expression for can be given in the form where is the total magnetic energy of the brake, which is equal to the derivative of the specific energy per volume of the magnetic system:
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