Actuator Design of a New AC PM Contactor with Energy-Saving and Noise-Free Characteristics
Developments in power electronic switches and lowcost actuator based on an electronic control module (ECM) have made it possible to design and implement modern control strategies for a new AC permanent magnet (PM) contactor. Such an attempt has made in this work for a colenoid actuator controlling the AC PM contactor. Certain important issues in design including the making signal generator and its amplifier, breaking signal generator and its amplifier, exciting coils, and a voltage regulator have been resolved. The proposed scheme is validated through extensive numerical simulations and a laboratory scale implementation.
AC contactor making speed measuring and theoretical analysis
Three-phase alternating current contactors (abbreviated AC contactor) are electrical devices, which are applied to many fields in large quantities. It is important to improve their life and reliability. Reduction of contact bounce of AC contactor is the key problem to increase its life and reliability. The test of measuring the making speed of contacts and iron cores of AC contactor has been performed. The samples are CJ20-25 model of AC contactor, and the applied voltage for measuring is 380 V during the experiments. The full closing processes of AC contactor were measured at different closing phases of the coil voltage. The test results show that making speeds of the moving contact and iron core varies with the closing phase of the coil voltage. For the CJ20-25, there is a closing phase (about 75 degree) where the making speed of the iron core is the lowest in the range of [0-/spl pi/]. In order to determine the best making phase to reduce the bounce speed of iron core as small as possible, the dynamic closing process of the AC contactor is analyzed theoretically by combining advantages of the two methods of "electromagnetic field" and "magnetic circuit", and the calculated results are in good agreement with the test results.
Mechanics of deformable directed surfaces
Abstract The paper develops a simple, yet complete and consistent non-linear dynamic thermo-elastic shell theory based on the concepts of a two-dimensional directed continuum. The constitutive equations are postulated in a general form. Stress-strain relations are derived using the equation of energy balance and the two entropy production inequalities, which are rewritten in a special form. The linear theory is discussed in detail. The structure of the stress-strain relations is presented in the most general form and then specialized to concrete examples, in particular, to the classical shell theory, using their invariance properties with respective to certain symmetry groups. The elastic moduli are determined by demanding the coincidence of the frequency dispersion surfaces obtained using the two-dimensional theory with the lowest foils of the corresponding surfaces resulting from the three-dimensional theory of elasticity.