Director Global Operations KEMA Laboratories
For more information:KEMA Laboratories
DNV GL KEMA Laboratories is celebrating its 90th anniversary this October.
Looking back over that history, it is interesting to note the role that testing has always played in enabling innovation in electrical equipment. And I’m proud to say the KEMA name has been at the forefront of this relationship. A good example of that is the circuit breaker, the component responsible for preventing a simple fault turning into a complete power system failure.
The most obvious trend in the power industry over the last 90 years is the ongoing rise in voltage to enable more efficient energy transport in ever larger quantities. Not long after KEMA opened its doors, Germany became the first country to install a long-distance 220 kV power line in 1929. In an admirable act of forward thinking and planning for the future, this line was designed from the start to be upgradeable to 380 kV. However, it was Sweden who took that voltage step first in 1952 when they opened a 1000 km line connecting the Harsprånget hydroelectric power station in the north to the big cities in the south of the country.
Hydroelectric generation – with its abundant, controllable renewable energy but typically in very remote locations – has often been the driver for big steps up in voltage. In 1965, Hydro Quebec in Canada opened the world’s first 785 kV line which ran from its Manic-Outardes dam to the Levis substation. Then in 1985, the Soviet Union broke the 1 million Volt barrier with its 1150 kV Ekibastuz-Kokshetau line, part of a high voltage network linking generating sites in Siberia and Kazakhstan to industrial regions in the Urals. This first-ever ultra-high voltage (UHV) line didn’t survive the break-up of the USSR, and has been downgraded to 500 kV.
Making a million
The world’s next attempt to move to UHV was also something of a false start. Encouraged by a major economic bubble in Japan, the Tokyo Electric Power Company designed a 1000 kV system to bring energy into Tokyo. But by the time the UHV equipment had been developed in the early 90s, the Japanese economy had stalled and the large-scale system never came to fruition.
Instead it was China that opened the first commercial UHV network in 2009, with a 1100 kV system of unprecedented scale. Right now, India is aiming even higher. It has finalized a grid connected test station and is preparing for a long-distance line operating at 1200 kV.
The role of testing
As voltages and network capacities rise, it becomes both more critical and more challenging to be able to effectively and safely isolate individual failures. Hence every step in the voltage evolution was accompanied – or rather made possible – by corresponding developments in switching technology. And at each step, the innovators needed to verify that these new technologies and the circuit breaker products based on them were up to their all-important job. Physical testing has always been the number one choice for delivering that verification, which has in turn required investment and innovation in testing methods and facilities.
KEMA was born in 1927, and ten years later opened its first High-Power Laboratory (HPL) in Arnhem, the Netherlands with a maximum testing voltage of 100 kV. Within a couple of decades, the decision was made to extend the lab. And when the Prince of the Netherlands officially opened the expanded facility in 1958, he saw a 380 kV breaker being prepared for testing.
Massive growth in the industry in the 70s led to another major expansion of the HPL, including facilities for testing at up to 550 kV, and created the world’s largest high-power laboratory. This enabled us in the mid-nineties to test the largest single-break circuit breaker in the world: a Japanese 550 kV design.
Ten years later, the Chinese 1100 kV system was conceived. Although such breakers are composed of multiple chambers, the specific metal-enclosed design in this system means the circuit breaker needs to be tested as a complete device. To ensure the most reliable testing possible, KEMA Laboratories took the bold but necessary decision to test the complete circuit breaker as it would be used: a component installed on the ground.
However, this would require an alternative to the traditional “synthetic” testing. In 2007, we ran a pilot project using a temporary “second stage”. Our existing installation was used to generate an initial 1 million volt kick, and then superimpose a second 1 million volt kick from the temporary source. First experiments were successful, demonstrating a full test of a 1200 kV circuit breaker.
A key lesson, though, was that even our biggest facility was only just big enough dielectrically to house the test object. In fact, ceiling lights had to be removed and the breaker’s bushings inclined at a smaller angle than designed to ensure enough dielectric space around it. This observation led to the decision to build a complete new, permanent installation, which was inaugurated in 2012. Having successfully demonstrated 1200 kV testing, the two-stage installation now allows fast and efficient “full-pole” testing of 800 kV circuit breakers.
The next major step in enabling UHV took place when we decided to expand the HPL to allow testing of other supergrid components such as 800 kV class power transformers. This included installing two generators and four transformers. Coinciding with our 90th anniversary celebrations, the first-ever UHV component tests took place at the expanded HPL earlier this year.
Director Global Operations KEMA Laboratories