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A device for controlling a two-winding polarized electromagnet is considered, and its disadvantages are noted. A circuit for the control of a single-winding polarized electromagnet is proposed in which the disadvantages of the existing control circuit are eliminated. Transient processes of charge/discharge of a capacitor to ensure actuation and reset of a polarized electromagnet are considered. The operability of the proposed circuit based on a composite transistor has been experimentally confirmed. [ABSTRACT FROM AUTHOR]

This paper considers an original valve electromagnet with integrated armature, designed to implement an electromagnetic overcurrent release of a circuit breaker. Theoretical and experimental studies of the proposed electromagnet have been carried out to determine the most important parameters of circuit breakers such as sensitivity and high-speed performance. Calculations and experiments have shown the possibility of increasing the sensitivity and speed of the electromagnetic overcurrent release based on the proposed electromagnet with integrated armature in comparison with existing structures used in modern circuit breakers. [ABSTRACT FROM AUTHOR]

Compensators of the repulsive electrodynamic forces of electrical contacts provide stable operation of automatic switches during the flow of short-circuit currents. This paper presents a contact device with electrodynamic compensation and its design model. The electrodynamically interacting parts of the compensator structure are the U-shaped bent ends of the current-carrying output tire and slow-moving contacts parallel to each other. The formula for calculating the repulsive electrodynamic force of electrical contacts is given. On the basis of the calculation model, the formulas for the electrodynamic effort of the compensator and expressions for contour coefficient of electrodynamic forces of compensator have been obtained. The condition of complete compensation of the repulsive electrodynamic force of contacts is presented. Calculations of the electrodynamic effort of the compensator of the breaker for a rated current of 630 А with a rated short-time withstand current of 40 kA have been performed. The compensator with the proposed configuration fully compensates for the electrodynamic repulsive force of contacts of circuit breaker, confirming the validity of relations obtained in the work. [ABSTRACT FROM AUTHOR]

Reducing the weight of the materials used in the creation of electromagnetic devices and decreasing the overall size of the latter greatly increases the attractiveness of low-voltage switchgear such as relays, contactors, and motor starters. These goals can be achieved by forced control of their driving electromagnets and the development of a technique for minimizing weight and size. In this paper, these problems are solved for a shell-type plunger constant-voltage electromagnet used as a drive. For the preferred region of the factor space of the source design data, a computational experiment was performed in accordance with a second-order orthogonal central composite design for eight variables. The polynomial models were developed for an optimal relative proportionality of a working air gap, the winding height and thickness, the outer collar height in fractions of an optimal core diameter, and the stop height in winding fractions. Examples of the calculation of the optimal electromagnet size minimizing its overall volumetric dimensions are given. [ABSTRACT FROM AUTHOR]

Thermal releases based on thermobimetallic elements (TBEs) form the current-dependent part of the protective characteristic of a circuit breaker. The design of a mechanism of free releasing and the characteristics of a thermobimetallic element are analyzed. The operating condition for the thermal release is formulated, which is based on comparison of the mechanical characteristics of an actuator and thermomechanical characteristic of TBEs. Experimental studies of thermobimetallic releases, which are analogues of the breakers to be developed, were carried out. Taking into account the results of these experiments, a design procedure of thermobimetallic release was developed, which is applicable for all types of TBE heating (direct, indirect, combined). The procedure makes it possible to determine the geometrical dimensions of a TBE and the methods of its heating, as well as the operating temperature of release depending on the rated current of the breaker. It has been noted that, to provide the possibility of operating current adjusting, as well as for reliable operation of circuit breakers under vibration and shock conditions, it is necessary to provide for the free running of TBE during design. Comparison of design and experimental data showed the accuracy of procedure, which is acceptable for practical calculations. [ABSTRACT FROM AUTHOR]

Studies of rare decays of charmed mesons are used to test the Standard Model and search for new physics. In the present paper we review the progress in the experimental methods of searching for the D0→μ +μ − rare decay in recent studies of proton-nuclear and hadron-hadron interactions. [ABSTRACT FROM AUTHOR]

Results obtained with the aid of the HERA-B detector, which operated at an internal target in a 920-GeV proton beam of the HERA storage ring at DESY (Hamburg, Germany), are discussed. About 164 million dilepton-triggered and 210 million minimum-bias events were collected over the data-taking time. These vast statistics made it possible to study in detail charmonium production in proton—nucleus collisions. Inclusive cross sections for open-charm, open-beauty, and ϒ-meson production weremeasured. The results are compared with the respective predictions of theoretical models. [ABSTRACT FROM AUTHOR]