Using CO2 to extinguish arcs in switchgear

September 2nd, 2014, Published in Articles: Energize

 

The high performance LTA 72D1 is the first high voltage circuit breaker to use CO2 as the insulating and arc extinguishing medium.

abb-123-09-2014ABB believes in minimising environmental impact over the entire life cycle of the product, which includes the three phases of design and manufacturing, use and end of life. ABB follows the ISO standards for product development and for giving environmental declarations.

For the LTA circuit breaker the environmental impact evaluation has been made with regard to the global warming potential (GWP). This is because GWP is generally the dominating category of environmental impact for products consuming energy during their lifetime. The result is expressed in CO2 equivalent emissions over the product’s life cycle.

Standards

The LTA circuit breaker fulfils IEC 62271-100 circuit breaker and IEC 62271-108 disconnecting circuit breaker standards.

Applications

The LTA 72D1 circuit breaker is designed for 72,5 kV distribution networks with short-circuit breaking current requirements up to 31,5 kA. It can be used as a conventional circuit breaker as well as a disconnecting circuit breaker in areas where reducing environment impact is high priority.

User benefits with ABB’s advanced technology

The LTA circuit breaker platform uses an optimised self-blast CO2 interrupter requiring extremely low operating energy and therefore lower operating forces within the breaker. It is developed using the same technology and similar components as applied in ABB’s widely used SF6 LTB product range, including the high conductivity, low resistive loss copper current paths.

ABB has the world’s most extensive range of mechanical spring drives for high voltage circuit breakers. The LTA 72D1 uses the same type of mechanical spring drives as applied in ABB’s SF6 LTB product range. This provides its customers with IEC Class M2, 10 000 operation lifetime drives which have common components with ABB’s extensive worldwide installed base of mechanical spring drive operated high voltage circuit breakers.

Simplicity with a common, single pressure dielectric and interruption medium

By virtue of the optimised interrupter design, the LTA 72D1 uses a common single pressure CO2 gas mixture providing both the interrupting function and internal dielectric withstand. The CO2 level is monitored directly and continuously online (similar to other ABB gas-based circuit breakers). No separate dielectric media versus interruption media level monitoring is needed.

Ease of installation and operation

The LTA 72D1 allows simple and adjustment free installation. The centrally mounted mechanical spring operating mechanism allows operators safe and convenient access to all circuit breaker status indicators and operating controls. No special training or tools are needed.

High switching performance

The LTA 72D1 offers the highest dielectric withstand capability of any (non-SF6) live tank breaker in its class, while at the same time providing long electrical contact endurance.

Design and manufacturing phase

The LTA circuit breaker is designed for minimum material usage for its required ratings. By replacing the conventionally used SF6 gas with CO2, the impact of any SF6 gas leakage during the filling phase is avoided. ABB’s factory is ISO 14001 certified for environmental best practices and we also conduct regular environmental audits at  its suppliers’ facilities.

Use phase

The high conductivity, low resistive loss copper current paths reduce resistive losses. The low operating energies used by ABB’s self-blast interrupters combined with the efficient mechanical spring drives result in lower auxiliary power supply consumption. By replacing SF6 gas with CO2, the impact of any SF6 gas leakage during the use phase is avoided. The LTA uses highly reliable gas sealing designs which are same as its SF6 gas circuit breakers and ensure a leakage rate of less than 0,5% per year.

End of life phase

By replacing SF6 gas with CO2, the complications of SF6 gas recovery and disposal are avoided. Improved recycling and disposal through clear declarations adjusted to different global boundary conditions. Replacement of SF6 with CO2 has been the predominant factor in reducing CO2 equivalent emissions over the product’s life cycle by about 10 t or 18% over a 30 year period.

Contact: Shivani Chetram, ABB, Tel 010 202-5000, shivani.chetram@za.abb.com

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