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Positive findings of ABB’s eco-efficient switchgear pilot project

ABB’s innovative AirPlus™, green alternative to SF6, shows positive results at Dutch utility provider, Liander

An ongoing field experience program of ABB’s innovative AirPlus™ insulation gas for medium-voltage secondary switchgear with Dutch utility provider, Liander, has already delivered positive results.

The purpose of the 36-month project was to verify that there is no impact of AirPlus on the life expectancy of the SafeRing switchgear. Data and gas samples gathered since November 2015 show that the insulation gas is behaving as anticipated, with no compromise on switchgear performance but with the added benefit of reduced environmental impact.

Combined with years of scientific research, the findings from two of the four SafeRing AirPlus units installed in compact wind turbine substations in Liander’s grid in Flevoland, Netherlands, look promising. Two of the four units are equipped with instruments to continuously measure and log gas density, temperature and pressure to monitor the performance of the switchgear. The findings indicate that using AirPlus insulation gas will not affect the normal switchgear lifetime expectation of at least 30 years, nor increase maintenance costs.

As a power utility for whom sustainability is high on the agenda, Liander actively encourages the development of sustainable grid solutions, such as SF6 -free switchgear. We are delighted to have partnered with them on this pilot project.

A key requirement of ABB’s eco-efficient fluoroketone-based gas mixture, AirPlus, which was developed as an alternative to the potent greenhouse gas, SF6, was that it would be possible to maintain the external dimensions of existing SF6 filled equipment. This makes it easy for customers to make the switch to an SF6-free solution.

The main technical challenges of replacing SF6 include reduced dielectric strength, thermal conductivity and arc-quenching properties of suitable alternatives. To ensure that degradation of the gas is negligible and does not affect switchgear performance, the long-term chemical stability and compatibility of the AirPlus with the switchgear materials has been carefully evaluated.

The installation of AirPlus switchgear in Liander’s grid, which has a service voltage of 20 kV and expected loads of up to 625 A, further validated the research results from ABB’s Corporate Research Centers.

In addition, at periodic site visits, the units are inspected visually and gas samples are collected for detailed laboratory analysis. The results show that the concentration of decomposition products remain consistently below the lowest calibration limit and the concentration of fluoroketone in the gas mixture remains comparable to the level measured when the units were manufactured. The samples from the first 1.5 years show that no significant deterioration of the units has occurred.

So, while the project still runs until 2018 and there will be more data to collect and analyze, results to date are highly encouraging. We look forward to continued cooperation between Liander and ABB in the completion of this field test, which will be critical in validating the use of AirPlus as an alternative to SF6 and in doing so, will help safeguard our planet for future generations.

Technical paper ‘RMU with Eco-efficient gas mixtures: Field experience’ first published at CIRED 2017, Glasgow, Scotland.

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