DCRT-200New development

Dynamic Contact Resistance Measurement (DCRM) of a circuit breaker allows to check the condition of the arcing contacts without the need to dismantle the circuit breaker without disassembling the arc extinguish chamber. This method effectively evaluates the condition of the main and arcing contacts of a circuit breaker by measuring changes in contact resistance during operation. The contact resistance is measured dynamically during opening or closing operations.

The use of DCRM reduces diagnostic time and costs, and avoids the complex consumable activities associated with disassembly of the arc extinguish device.

The long and reliable operation of high-voltage SF6 circuit breakers, which are designed to operate for up to 30 years, significantly depends on the condition of the arc extinguish chamber and the arcing contacts. These contacts are a key element in the arc extinguishing process during closing/opening operations and are exposed to arc erosion.

That is why user manuals developed by leading manufacturers (ABB, SIEMENS, AREVA, UETM, ZETO and others) prescribe mandatory control of their technical condition during each maintenance.

Moreover, according to the international sources, it is recommended to carry out DCRM inspection every year, because the arcing contacts wear out even in normal operation mode and when short-circuit currents are interrupted. In addition, the arc can both reduce their size and damage their surface.

SF6 circuit breaker chamber movable arcing contact length shortening can lead to critical consequences. During the “open” operation, the opening of the movable and fixed contacts will occur “with compensation”, delaying the formation of the necessary gas pressure in the chamber. This, in turn, will reduce the speed of the gas flow blowing the arc, increase the duration of its burning and, in the most unfortunate situation, cause an explosion.

The erosion formation on the movable or fixed contact of the SF6 circuit breaker arc extinguish chamber is also a serious risk. This may increase the contact resistance of the movable/fixed contact pair, resulting in rapid wear of the arc extinguish chamber.

DCRT-200 combines ease of use, workflow efficiency and significantly reduces labor costs. Automated functions minimize the risk of measurement errors. The built-in rechargeable battery provides autonomy, which is especially convenient when working in the absence of permanent power supply.

For more than 30 years SKB EP has been developing methods and devices for high-voltage switching equipment diagnostics, that is why the PKV group devices are widely used by specialists during scheduled and complete maintenance to control time, speed and travel.

 
DCRT-200 tester is an additional accessory that extends the functionality of PKV/M7 device. Combined operation of DCRT-200 with the PKV device provides complete and detailed testing of circuit breakers, including measurement of dynamic contact resistance.

PKV/M7 is supplied with special software for PC. The software is a convenient tool for working with measurement results and analysis.

DCRT-200 diagnostic results are presented in the form of graphs, which can be used to determine the contact length and the presence of surface erosion.

The obtained graphs are instantly displayed during the measurement in the software on the computer. This makes it possible to analyze the diagnostic results obtained on site and make a conclusion about the need for further repair of the chamber.

DCRT-200 has been designed, manufactured and tested in accordance with the following requirements and regulations:

•  In accordance with GOST IEC 61010-1-2014 Interstate Standard. “Safety of electrical control and measuring instruments and equipment”;

•  In accordance with GOST R IEC 61326-1-2014 National Standard of the Russian Federation. “Electrical equipment for measurement, control and laboratory use”.