Shhka problems

 

The brush-pin is ranked first in damageability among the generators nodes, not only in Russia, but also abroad. This follows from the analysis of technological violations related to damage to generators during the seven-year observation period from 1998 to 2003. This fact is corroborated by data from foreign sources.

All attempts by individual professionals to find a simple and cheap solution do not produce reliable positive results. The use of advertised brushes with screw-forged leash (with the index +) did not provide at CHP-21 Mosenergo 100% reliability of brush-contact devices, as on one of the generators was recorded the case of circular fire.

Attempts to apply the Best Western's brushes also do not provide the required reliability of work. At Perm Gres in May, 2005 shortly after installation on Turbogeneratore t3v-800 brushes of one well-known foreign manufacturer on brush-contact device The circular fire has arisen, and the block has been stopped for replacement of brushes on domestic.

At the same time, the use of Shhetkoderzhateljamis with permanent press springs also cannot be a solution because, on the western Turbogeneratorah, problems with brush-contact machines are Relevant.

 

The first and main conclusion to be drawn from the above facts is that if for many years the same professionals cannot find solutions to the problem, they are "looking not where they lost or where they are."

 

The main causes of the situation are as follows:

  • The basic knowledge of the physical processes occurring in the sliding contact was formed on the basis of experiments carried out no later than the 60-70 years of the last century;
  • The process studies in the sliding contact were conducted at the laboratory booths, where it is not possible to model all the conditions in the actual technical atmosphere of the machine rooms of power plants, but also the variety of excitation systems and their regimes Work;
  • The designers of the domestic brush-contact apparatus did not pay due attention to the electrical processes in the brush-contact apparatus, as well as to the physical causes of accidents at Shhka generators;
  • Brush-Contact vehicles have been methodically and technically completely out of the automated pi of power plants, leaving virtually no technical information on the dynamics of the Shhka in operation. This does not allow analysis of the current state of the Shhka and reliably predict its performance.

A comprehensive survey of the work of the brush-contact apparatus of all generatorss in operation of the six atomic stations of the rosenergoatom concern, conducted by our specialists together with the PMU Vei (Moscow) in 2004-2006 years, allowed Obtain fundamentally new data about the work of brush-contact machines based on the results of the tool measurements. In addition, it was important to conclude that, due to the lack of reliable information based on the results of instrumental measurements, many specialists have developed a number of misconceptions over the years about the processes taking place in brush-contact The main of which is the following:

A brush current working as part of an ensemble parallel to working brushes is proportional to the rotor, i.e.

Where is a constant value that depends on the resistance of a particular brush.

As the current Russian and foreign studies have shown, a particular brush, working in a brush-contact apparatus, tends to be "highly unstable" in terms of foreign researchers. i.e. The short-term resistance of a particular brush (including sliding contact resistance) is non-linear and depends on many external factors.

There are two principal ways to solve the problem of securing a stable current in the sliding pin of each brush and even current distribution between the brushes.

One: In laboratory conditions, in the climate chamber, to investigate the work of the brush-contact apparatus and to determine the optimal modes. On the basis of the data obtained, develop a serial brush-pin which is placed in a sealed enclosure with a technical atmosphere that provides optimum conditions for the stable operation of the sliding contact. In this case, the brush-pin may be practically unserviceable (except for a brush substitution procedure due to natural wear).

Leading world producers of generators (Siemens-Westinghouse, Alstom, Toshiba) provide all new turbogenerators capacity above 300 MW with brush-contact systems. In this case, the brush-contact apparatus has been sealed, with a controlled and controlled technical atmosphere. The composition of the technical atmosphere, humidity and temperature mode provide the best and most reliable work for sliding brush contact. Such designs are based on a set of special studies. Technical information on such research, as well as on the system of technical atmosphere of the brush-contact apparatus, is the property of the firms and is not published in open sources. Visits by technicians to stations with new generators are limited by the scope of the advertising prospectus.

A new brush-pin system with air filtration and air-conditioning system has now begun to develop in the JSC power. It should be noted that the designers currently do not have reliable information on the best brush performance.

The development of a new construction of a sealed brush-contact apparatus is a decision of principle, but it requires considerable material and time. This approach is therefore primarily oriented towards newly created turbogenerators.

The second path is oriented towards working turbogenerators, equipped with the serviced brush-contact machines.

This path in turn has two parts-technical and organizational-methodical.

The technical part is to equip the brush-contact apparatus with a set of sensors to provide quick and reliable information on the stability of the current of each brush and the distribution of the rotor between the pins of the contact apparatus.

The organizational-methodical part is the fundamental change in the general attitude to diagnostics of Shhka. You need to establish a Shhka service on the results of tool controls with feedback elements. The selection of the brush type, the number of brushes, the selection of press and other activities should be conducted with a view to improving the stability of the sliding contact and the uniformity of the current distribution. Shhka diagnostics should become an integral tool for servicing the Shhka.

Since the development of the automated diagnostic system for the brush-contact apparatus depends to a large extent on the capabilities of modern microprocessors, whose availability has become the same throughout the world, it can be assumed that The automated diagnostic systems will be widely disseminated and adapted to existing automated PI stations in the coming years.

As a foreign example, the installation of the online-monitoring systems between the separate brush-contact machines at the two Turbogeneratorah nuclear power plant "Temelín" (Czech Republic) can be cited. It should be noted that the systems were installed almost immediately on two of the stations (18.7.2005, 9.10.2005) without waiting for the results of the pilot operation of the parent sample. This is due to the obvious utility of these systems.

The automated monitoring system of the brush-contact apparatus (AFS Shhka), developed and built by our specialists, provides all the necessary operational information to the staff as the entire brush apparatus in General and the work of each brush. For more information about AFS Shhka, read the appropriate topic.