PNRPU Bulletin. Electrotechnics, Informational Technologies, Control Systems

It is known that the misalignment on the contact elements in high power switches on breaking the contact results in a lower reliability and durability We investigate the relationship between the change in the misalignment on the contact elements and the change in the current density in regards to the dynamic behavior of the contact. The analytical model for electrical contact between elements in high power switches describing the impact of the relative misalignment on the change in the current density in the dynamic contact area. The numerical calculation and verification demonstrate the critical influence of the misalignment of the contact elements on the current density, and therefore when planning to enhance reliability of the electrical contact it is important to make allowance for this result. The example of the crushing the surface of the contact elements under misalignment is considered in this paper.

The Boolean algebra of logic, logic functions are the basis of a mathematical apparatus of digital electronics and circuit engineering. At the beginning, from the moment of the invention of the relay in the middle of the 19th a century, they were implemented by contact-relay diagrams - serial-to-parallel and bridge, then after creation of transistors - at the microelectronic level. Small-scale integrated microcircuits - "hard" logic, then chips of average integration scale including "flexible" logic were created. In the 1970s the first programmable logic arrays which were used further in larg-scale integrated microcircuits were released. Such structures are widely used during creation, for example, of control and monitoring devices. Programming was first once, at the factory, and then there was the possibility of programming by the user with the help of a special programmer. Then reprogrammable logic arrays were developed electrically. They are used also in the CPLD (complex programmable logic devices) programmable logic integrated circuits (PLIC), unlike FPGA (field-programmable gate array) where implementation in the form of a tree of the transferring transistors is used that in essence is the multiplexer selector or a fixed memory digit capacity of one bits with n address inputs. It is of interest to study the features of programming logic matrices in CPLD in order to consider the possibilities of increasing their fault tolerance in special highly reliable applications. The principles of programming the logic matrix are analyzed in the article, the simulation of the implementation of the conjunction in the NI Multisim 10 system of the National Instruments Electronics Workbench Group is performed, and the fault-tolerant implementation of the logic matrix is proposed and evaluated.

The article investigated to the integration of prediction models into the information infrastructure of production systems for decision support in an automated mode. The actuality of the work is related to the increasing volume of accumulated statistical data, the complexity of working with big data sets in systems that are not integrated into the IT infrastructure of enterprises and the importance of using them for the improving the quality of management decisions. The research is based on the important data sets and models for decision making, and integration they into the existing information infrastructure based on a set of IT solutions or software developments. To approbate the proposed approaches, was observed the problem of the purchase amount on the basis of a prediction model and integrates it into the IT infrastructure of the enterprise. The solutions showed several possible ways of using models and information infrastructure depending on the task and organization of the IT infrastructure, as well as the flexibility and practical applicability of the proposed approach.

Crane-manipulator engines are more popular in different fields of modern technique. Crane-manipulator’s boom with two or three joints allow to work at limited space. Often last factor is defining in equipment choice for work. More than usually machines with crane-manipulator combine hoisting mechanism’s and truck’s features that allow to optimizing number of engines in handing operations and transporting of materials. But crane-manipulator engines have some problems inhered in all crane engines and specified for separate engines: rocking of freight, hydraulic vibrations crane-manipulator’s boom elements, cable’s breakthroughs, hydraulic winch’s work limitations and other. Some crane-manipulator problem’s solutions reviewed in paper. This solutions are used in crane-manipulator or other hoisting engines such as overhead cranes. The method’s merits and demerits are listed in paper. More than for methods used for non-crane-manipulator hoisting engines limits of application in crane-manipulator engines defined in paper. New microprocessor-based control system design chosen as main crane-manipulator engine modernization strategy. This modernization type don’t request powerful changes in crane-manipulator engine’s construction such as crane-manipulator boom replacement. This is main difference of this method from some methods reviewed in paper. This method not applicable for every crane-manipulator engine. Crane-manipulator engine of robotized hoisting complex has same features that listed in paper that allow produce integrate microprocessor-based control system. This features reviewed in paper. Also the paper contents structure of control block used for crane-manipulator engine’s modernization.

The article introduces the research of the architecture of programmable logic integrated circuits based on the Look-Up Table. There is described the existing problem of programmable logic integrated circuits of the type field programmable gate array, which consists in the lack of orientation of logic elements based on LUT to the system implementation of logic functions. The article describes in detail LUT with one variable, characterizes it, reports the realization of orthogonality of signals in the branches of the tree of transistors. There is proposed an improved method of implementation systems of logical functions defined in a perfect disjunctive normal form in the field programmable gate array based on signal transmission in the other direction. The DC-LUT element is offered, a detailed description of the structure is given, as well as its characteristic. Realization of systems of logic functions is provided by a block of disjunctions of the constituent of a logical function, its description is also given. A new DNF-LUT is proposed for implementation the functions of a large number of variables. There is described an improved structure of the new DNF-LUT modification, which consists of the adaptation to the level of the transmitting transistors used in the LUT and the original encoding of conjunctions in disjunctive normal form. The programming of one variable for the proposed structure of DNF-LUT is considered. There is drawn a conclusion about the advisability of applying advanced methods for the implementation of systems of logic functions in programmable logic integrated circuits of the field programmable gate array type.

The problem of effective steam temperature control at the out of boiler is considered in the article. The temperature of superheating of steam at the outlet from the superheater is one of the most important parameters that determine the economical operation of the steam turbine and power boiler. Automatic regulation of steam superheating should ensure that the temperature of superheated steam is maintained within the specified limits, regardless of the load of the boiler. The metal of the pipes of the boiler is in particularly difficult operating conditions. Increasing the temperature above the allowable values can lead to an accident due to the appearance of creep of the metal, increased thermal expansion and a number of other reasons. From the strength conditions of the metal pipes of the superheater, the steam pipe and the turbine it is important not only to maintain the temperature within the specified limits, but also to prevent its sudden changes. At the same time, a significant lowering of the vapor temperature in front of the turbo unit leads to an unacceptable increase in humidity in the last stages of the turbine and erosion of the blades, which results in an increase in the specific steam consumption, and in some cases, an emergency stop of the turbine unit. The article describes the solution of the problem of precise control of the steam temperature at the outlet of the superheater and, at the same time, the protection of the metal of the preheating stages of the superheater. To achieve the set goals, the following tasks are solved: introduction of temperature correction before the second injection, automatic adjustment of the regulator coefficients depending on the boiler load; the introduction of the anti-backlash unit. The article describes the functional diagram of the automatic steam temperature control system. The results of technical studies were obtained with the help of the SARGON software and hardware complex.