Celebrating 10 years of DualGround™ circuit breaker timing with DCM technology

Electrical Tester – 31 July 2017

Megger is celebrating 10 years since it launched, in 2007, its very first circuit breaker test instrument featuring dynamic capacitance measurement (DCM) technology, which makes safe quick and accurate circuit breaker timing possible, with both sides of the breaker grounded, in more situations than ever before. To find out more about the story of this groundbreaking technology, we’re interviewing Nils Wäcklén, Product Manager at Megger Sweden AB, who was involved in the development of Megger’s patented DCM technology from its earliest stages.

ET: How did DCM come about? I imagine there was a lot of groundwork and development needed before this innovative technology was ready for the market.

Nils: To be perfectly honest, it had been possible to measure timing with both sides of the circuit breaker grounded since 1992 when we introduced the DRM (dynamic resistance measurement) technique. But back then the results were not always consistent and reliable; they were very much influenced by the environment and the application. DRM is, in fact, the technology still used by most of our competitors. But one of our engineers came up with the idea that if we viewed the breaker as a variable capacitor then we’d be able to get better, more reliable and more repeatable timing measurements for all kind of breakers. And, after a lot of development work to turn his idea into a practical reality, he was proved right.

ET: How did customers react to the first instruments incorporating DCM when you launched them in 2007?

Nils: They were sceptical! When they saw the measurement set up for the first time, it was hard for them to believe that it would deliver reliable results – or indeed, any results – for timing. This is because it’s the same measurement set up that’s used for conventional timing measurements except that both sides of the breaker are grounded through low resistance connections, which would seem to make timing measurements impossible. However, with innovative technologies like DCM, the impossible becomes possible and the scepticism of our customers was quickly dispelled when they saw our new instruments in action.

ET: What are the benefits of DCM?

Nils: Without a doubt the biggest benefit is greatly increased safety for substation engineers. With the DualGroundTM measurements made possible by DCM, engineers can work with both sides of the breaker grounded, which means they’re protected against receiving dangerous shocks from, for example, voltages induced in the breaker by current flow in nearby live conductors. This is enormously important in the substation environment. Other key benefits are that DCM saves time, since it’s no longer necessary to remove one of the ground leads before making a measurement and reattach it afterwards, and that DCM can be relied upon to give accurate repeatable results.

ET: How commercially successful are instruments that incorporate DCM?

Nils: We’ve sold almost 700 units since they were launched, which can definitely be considered as a success for new technology in a conservative industry. However, we still think that there’s huge potential for selling many more instruments that incorporate DCM, because DualGroundTM measurements offer such enormous safety benefits. Sadly, there are organisations out there that fail to take these benefits seriously until they experience an incident or accident – possibly with a tragic outcome – that forces them to think again. 

ET: How do you see the future of DCM technology?

Nils: Well, we very much want people to invest in instruments that incorporate DCM technology and offer DualGroundTM testing without waiting for an accident to happen. Fortunately, with the growing attention that organisations are now giving to safety, we’re finding that this message is being accepted more and more. So the future’s bright for DCM and DualGroundTM! However, we’re not going to rest on our laurels, and we’ve just embarked on a new publicity campaign that will make the benefits of DualGroundTM testing even more widely known. It may be a decade old, but DCM is still great technology that’s well ahead of the field!

Join our celebration by attending one of the roadshows we doing around the country. Our next one is in Perth, Scotland. You can find out details and book your space by clicking here