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Electric Circuit Breakers

#1082


Carrying out Research on Developing the Electric Circuit Breakers Based on the Shape-Memory Materials

Tech Area / Field

  • MAT-ALL/High Performance Metals and Alloys/Materials
  • MAN-MCH/Machinery and Tools/Manufacturing Technology

Status
3 Approved without Funding

Registration date
13.08.1997

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • Institute of Physics of Strength and Materials Technology, Russia, Tomsk reg., Tomsk

Project summary

The objective of the Project is to carry out research on developing a new advanced design and a pilot technology for manufacturing electric circuit breakers (ECB) based on the use of materials with shape memory effect (SME). The design and technology are intended for application in different civilian branches of industry.

The entire Project will be mainly performed (83%) by RFNC-VNHEF specialists formerly engaged in nuclear weapons (NW) development. The Project implementation win serve for the aims of redirection of their scientific and technical activities to carrying out fundamental and applied research and development of designs and technologies for peaceful purposes. At the same time it is anticipated to establish long-term perspectives for integrating them into the international scientific community.

Participation of SSC-IPSMT SD RAS specialists having the leading position in Russia in studying the SME materials will allow achieving better technical results in the Project implementation.

The Problem Description

Safety of all electric circuits is ensured by the breakers, which operate automatically as the current force exceeds the critical level. Performance of most ECB is the based on employing the property of bimetal to spontaneously deform by bending when heated.

The main defects of such breakers are related to thermomechanic characteristics of bimetals:


- even deformation of the working element under temperature changing;
- small magnitude of linear shifts under heating;
- low thermal resistance resulting in the loss of efficiency under overheating;
- complication and high cost of technology for manufacturing bimetals of high quality.

These defects in the aggregate lead to decreasing the operation reliability and as a result, cause the necessity of industrial adjustment of each working element and its regular correction in the breaker operation, and also define an inevitably high percentage of rejects while manufacturing the working elements.

Unlike bimetals, SME materials possess unique properties:


- high degree (SO times higher than in bimetals) of reversible deformation limited by the narrow temperature range;
- stability of thermomechanic characteristics.

The idea of this Project is to create more reliable electric circuit breakers of a new generation using SME materials.

In this Project we plan to make ECB on the operating currents up to 100 A.

Technical Approach and Methodology

Research technique is of experimental-computing type. The main problem in manufacturing ECB based on the SME alloys is to obtain material possessing chemical and phase composition required and to choose a scheme of loading and deformation of the working element. Furthermore, thermal treatment conditions and other technologic methods are of great value. High sensitivity of SME characteristics to the above-mentioned parameters defines the necessity of using a wide range of standard and unique methods to determine regularities and peculiarities of formation of the alloys structure and properties. The Project contractors possess all research techniques and production to technological basis required for manufacturing pilot-industrial lots of alloys.

Level and Feasibility of Scientific Technical Approach

Development, research and application of SME alloys are one of the prior fields of modern materials science and technology. The activities of scientists and engineers in contracting institutions as and all over the world in this field have provided creation of the products, equipment and technologies, being new in principle based on the SME alloys, which can be applied in aircraft and space, mechanical and instrumental engineering, medicine and environmental protection, household appliance engineering and consumer goods.

Research results of the Project contractors were presented at the international symposia, conferences and workshops: Shape Memory Alloys, China, 1994; International Conference on Martensitic Transformation, USA, 1993 and Switzerland, 1995; Advanced Materials and Processes, Russia, 1995; Material with Shape Memory Effect, Russia (Sankt-Peterburg), 1995.

The Project will be implemented by highly qualified personnel (including 3 Doctors and 717 Candidates in Physics as and Mathematics, Technology and Philosophy). The participating personnel is distinguished for carrying out fundamental and applied research of high quality as well as for a wide scale of introducing SME materials and designs. This ensures a real feasibility of the proposed scientific- technical approach.

Validity of Applying Techniques Making the Basis of the Project

Shape memory effect, which manifests itself in some alloys based on titanium, copper silver and gold, is considered to be a physical basis of the electric circuit breakers of the new generation. In the narrow aspect the SME is thought to be a phenomenon of restoration of the previous deformation on of me object (for example the ECB working element), which is initiated at the expense of temperature change.

Phenomena of reversibility of large inelastic deformations of the SME alloys air defined by the development of direct (under cooling) and reverse (under heating) phase transformations of martensitic type. At the same time martensitic transformation parameters (temperature, lattice deformation, hysteresis) are genetically connected with SME characteristics such as temperature and magnitudes of accumulation and return of the working element deformation.

In this Project it is planned to use an alloy on titanium nickelide base for manufacturing the ECB working element Among other SME alloys titanium nickelide alloys have a wide range of temperature change of SME manifestation (up to 400K), high magnitude of reversible deformation (up to 10%), high cyclic and time stability of the memory properties. That is why Ni-Ti alloys are currently preferably applied in industry and medicine.

Expected Results

Scientific value will lie in the following:


- experimental and computing techniques win be worked out to study the influence of various factors on the SME manifestation;
- new data on chemical and phase composition and SME manifestation under different temperature-rate conditions of loading and Ti-Ni deformation will be obtained.

Commercial and technical value will lie in the following:


- design of ECB of a new generation will be developed;
- a technological process will be worked out and on this basis a titamum-nickelide alloy with a phase composition ensuring precision SME characteristics will be produced;
- the influence of different conditions of thermal processing and technological methods (for instance, rate of setting the shape memory) on SME manifestation will be investigated.

In our opinion, this will provide a possibility for making up a competitive-capable design and technology to manufacture electric circuit breakers using SME materials. Such simple and secure devices are required both in household appliance engineering and in atomic and conventional power engineering as well as in metallurgy, coal mining and other branches of industry. Licenses on manufacturing the breakers may become the object for sale on the market. Moreover manufacture of breakers jointly with foreign companies and their selling on the market are also possible.


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