Spider Maintenance: How Arachnid Robots Help Keep Electricity Generation Stable
21st April, 2020
It’s called the GenSPIDER®: a 19.9 mm-thick arachnid robot that realizes drastic thinness and precise movement with minimal vibration. Mitsubishi Electric has developed the ultra-thin spider robot for optimizing machine maintenance processes. Robot involvement has reduced the typical one to two months required for electric generator inspection to just six days, and the adroit arachnid also adapts to maintenance needs for a variety of Mitsubishi Electric’s mid- and high-capacity electric generators. Here, here are details of the technology that makes this engineering feat such a marvel.
Just Six Days!
As of late, consumers and companies place emphasized importance on products’ and services’ sustainability, but one point worth contemplating is how to manifest sustainability in concrete, realistic terms. All products, bar inherently disposable ones, require inspection, maintenance, and repair. This of course means that cars, elevators, traffic signals, and all variety of devices intertwined in people’s everyday lives receive regular checks. The same concept applies to electricity, a fundamental element of daily life; electric generators, which create electricity, similarly require periodic maintenance. But generators are not only incredibly sophisticated, they can be huge vast and loaded with state-of-the-art-technology – and with all factors considered, conducting an inspection of the device can consume exorbitant amounts of time.
One example can be seen in the realm of thermal power, which accounts for over 60% of all electricity generated in Japan. Thermal power makes use of a massive turbine generator nearly 5 meters in diameter, 10 meters deep, and weighing nearly 400 tons. A single generator produces enough electricity for two million households every day. The engines create electricity by way of a steam turbine or gas turbine, the force of which turns a component called a rotor, found within another part – a stator. Maintenance for turbine generators is generally carried out once every four years, with the process itself taking approximately one to two months.
And there is a reason for this. To inspect the apparatus, crew members must begin by first removing the rotor – nearly 100 tons – using a crane hanging from the power plant ceiling and suspending it in the air: an effort requiring two days’ time and a team of 10 skilled workers paying scrupulous attention to each detail. After extracting the rotor, inspectors move into close inspection of each component, performing repairs or replacing parts as necessary. Their initial check completed, team members work to return the rotor to its original position – another task taking one to two days on its own.
As made evident above, a single maintenance run requires vast amounts of time – but it’s not only that. Inspecting a generator means shutting it down and rendering it incapable of creating new electricity. The cost of the maintenance process is also heavily taxing. With all of these factors considered, reducing outage periods and cost by improving maintenance processes was once a matter of pressing concern.
But not any longer. With the creation of the GenSPIDER®, an ultra-thin electric-generator inspection robot, inspection man-hours have seen a drastic decrease; the little invention has succeeded in reducing overall inspection time to approximately six days.
Why has this arachnid robot been so successful at this? The secret lies in its ultra-thin, 19.9-millimeter body, allowing it to crawl within the tiny 20-to-100 mm openings present throughout the stator and the rotor. Such technology removes the need to pull the rotor out, a task that previously required 10 engineers and two days to complete. Conventional inspection robots had thicker frames (nearly 30-millimeters thick), rendering them incapable of making their way through the stator and rotor’s smaller openings and performing maintenance within.
But this isn’t all that sets it apart technologically. For example, inspection robots move through the stator-side of the machine, which is riddled with ventilation ducts – but their small wheels, when left bare, have a way of getting stuck in these crevices. Such movements lead to an increase in undesirable vertical vibration. Here, the GenSPIDER®’s crawler movement system provides a solution; engineers have inserted a flat plate between wheels which presses the belt on the wheels to the surface. This has not only minimized vibration and reduced the impact on the level of precision required here – but also increased propulsion. Such features allow even a smaller engine to exhibit the power needed for the job.
One can also find coils within the stator, held into place with resin components known as wedges. Wear over time causes the wedges to loosen, leading to coils vibrating more than usual – an effect that can lead to undesirable results. The GenSPIDER® addresses this problem with its tapping mechanism, a technology praised for its ability to tackle loosening wedges. At this step of the process, conventional inspection robots employed for the job once had to lightly tap these apparatuses with claw-like parts in repetition – the force of impact, as you can expect, was minimal. This spider robot, however, has succeeded in increasing tap impact by nearly tenfold, allowing for higher precision at this step of the process.
The GenSPIDER® additionally features LED lights with miniature camera devices on its front, allowing crewmen to perform visual inspections on any miniscule scrapes, foreign objects, powder, or other elements in the stator.
Making Infrastructure Stabler
Robots have grown to take on tasks that humans struggle with – lifting heavy loads, traversing into places that people can’t fit, working in tight spaces, and more – and engineers work to develop these mechanisms around such limitations. The GenSPIDER® exemplifies this; it fits into spaces less than 20 mm wide (barely large enough for the human arm to fit into) and performs highly sophisticated visual checks, tapping work, and other vital maintenance tasks on a level that is on a par with, or surpassing, that of maintenance staff workers.
And for all of its prowess in revolutionizing this typically daunting maintenance process, the GenSPIDER®’s size is deceptively compact: easily small enough to carry by hand. And work that once took 10 people to complete now requires as few as only 2.
The GenSPIDER® has proven to shine at what it does – greatly reducing maintenance times and cutting down on personnel costs as well as performing more in-depth checks and conducting predictive maintenance. Electricity plays a crucial role in people’s day-to-day lives, meaning that consumers require the resource in a stable supply. The GenSPIDER®, in spite of its compact size, plays a multi-faceted role in making these generators work. One could say that this ultra-thin spider plays a vital part in keeping life uninterrupted and giving people the peace of mind they need.
(This article was originally published on March 31, 2020.)
The content is true and accurate as of the time of publication.Information related to products and services included in this article may differ by country or region.