Carbon materials and products
The Ukrainian manufacturer of carbon materials and products, is looking for partners to test a new generation EF-68 graphite-polymer universal material for electric motor brushes.
The Ukrainian company was founded in 1993. The manufacturer produces brush materials for electric motors. The brush-and-knot assembly is one of the most important elements that affect the operational properties of electric machines and largely determines their resource capabilities. The analysis of failures in operating conditions, for example, for traction electric cars of direct current in railway transport, shows that on average about 20% of the total number of failures are the faults of the brush-collector unit. Features of the operation of electric machines assume a periodic replacement of electric brushes, which are subject to strong electroerosive and mechanical wear. The process of brush replacement is very labor-intensive and requires the stopping of the technological process in the industry if there are no reserve capacities or rolling stock for planned and unplanned repairs. The main reasons for the decrease in the brush life, and as a result of increasing financial and labor costs for the operation of electric machines, remain the problem of breaking the switching stability and wear resistance. In connection with the increase in specific loads, while maintaining mass-dimensions of traction motors, the issues of increasing the resource of the brush-collector unit are put on the first place. Electrographic materials from which electrographic brushes of electric machines are made have a sufficiently high porosity that allows them to be impregnated with various organic resins and inorganic substances or metals. Impregnation improves the physicomechanical and collector characteristics, such as resistance to high temperatures, operating life or coefficient of friction. As a result, electrographic brushes have been widely used in the field of electric transport, in high-speed generators (wind generators) and turbogenerators, various converters, traction and crane electric motors etc. Based on 25 years of experience in the production of carbon materials by the company, a new technology for creating a brush graffiti-polymer material EF-68 was developed jointly with the leading enterprises and universities of Ukraine, which differs from the generally accepted ("classical") technology for the production of brush materials of electro-graphite class of world producers. In the new production technology, the graphitization stage is excluded, which is the longest, expensive, energy-intensive, and complex, since it involves the operation of special furnaces with a working temperature of up to 2,700-3,000 degrees Celsius, and also causes great environmental damage to the environment. The use of the new technology, on the one hand, allows the use of relatively expensive original components, which several times improves the performance characteristics of electric machines, and on the other hand, remains at the bottom price position compared to current prices of world manufacturers of brush material. In addition, the high parameters of arc resistance of the EF-68 material allowed to increase the current load in the contact zone of the brush-collector unit and opened the prospects for constructive expansion (modification) of the nomenclature of electric motors, which in the conditions of high competition in the world market of electric machines, in turn, will to have as a result a significant advantage for the manufacturer.
The company wants to apply for an R&D project such as Horizon 2020 (SME instrument Phase 1).
Advantages:
Carried out sea trials of rolling stock of metro and railways of Ukraine, railways of Mongolia in 2016-2017 with brushes made of EF-68 material showed:
- high wear resistance of brushes increases the between-repair mileage of a rolling stock unit from 100,000 km to 300,000 km;
- an increase in the time between the repair life of electric motors from 1.5 to 10 times in comparison with the life of brushes from materials of other world manufacturers.
Type and Role of Partner Sought:
As part of the joint participation in the first phase of the European Union's "Horizon-2020" program, we propose joining the consortium to test this brush material in your company (or your partners' company) by conducting bench tests to confirm the performance characteristics of the EF-68 material. To conduct bench tests, it is sufficient for the enterprise to have a test bench for collector motors under switch load conditions, a set of measuring equipment for electrical parameters.
Bench tests are proposed to be carried out in accordance with the developed program in 2 stages with a total duration of 10 working days:
1 stage, up to 7 working days, 50 hours of work, up to 8 hours daily. Measuring the wear of the electric brush when the electric machine is operating in the standard mode.
Stage 2, up to 3 working days, up to 8 hours daily. Measurements in three current load modes (60%, 100% and 140% of the rated current (standard)), at 50% and 100% of the collector speed (from nominal):
- the voltage drop between brush and collector;
- the degree of sparking of brushes, as well as the identification of zones without sparking commutation.
To carry out the tests, a set of laboratory samples is provided from the company and 2 representatives are sent to the test group.
