In the past 100 years, environmental sensors have mainly been used to forecast the weather. In the past ten years, these sensing technologies have spread significantly – they now help to optimize many industrial processes. Renewable energy (sun & wind), building automation, high-speed train management and driverless cars are important examples. All of them, and this is crucial, require environmental sensors with features that are very different from those of traditional weather sensors. This blog post gives you a simple instruction how to ensure to get precise data and how to deal with your weather sensor equipment the best way…
SHM30 snow depth sensor in Antarctica (photo: Alfred-Wegener-Institut, Helmholtz-Zentrum Bremerhaven)
A lot of sensing technologies have changed recently: Ultrasonic wind measurement replaces cups and vane systems, closed anemometer designs offer better protection from bird attacks, contactless radar and opto-electronic solutions come into fashion and the laser technologies are growing. Most of them need to be remote-controlled and evaluable in real time requiring proactive management to avoid data gaps. Other trends are the further automation of different applications through the so-called IoT (Internet of Things): Soon, it will regulate the amount of de-icing material spread on winter roads and driverless cars for example – all with the principle: install and “forget”. Therefore the sensors must run absolutely reliably for plenty of years.
For environmental weather data networks, in the past the precision of the delivered data was most important. Today, this requirement alone is not enough: survivability, long-term stability and a maintenance-free operation are required. The different versions of the Lufft weather sensors fulfil all those needs in a compact way. But how to make sure, that such control devices keep what they promise?
We guarantee for it through factory certificates which are delivered standardly with every sensor. Furthermore we offer traceable and internationally accepted test reports which are issued by our independent DAkkS-accredited laboratory. Also other third parties such as NIST or SCS can be engaged. They certify the calibration of important measurements such as air pressure, relative humidity, temperature or wind speed and direction through calibration papers (“performance certificate”) – typically for every single sensor.
After the installation of e.g. weather stations, it is highly recommended to do an on-site verification. For this, traceable equipment is required to do a comparison between the installed and an highly accurate reference sensor. A single point comparison is not enough, it is much better to do a two-point calibration. Also, the on-site check should be performed over a period of at least one hour. As outdoor weather sensor are often in use for over ten years and exposed to extreme conditions, manufacturers should carry out HALT (survival) tests, ice-free tests and MTBF tests (mean time between failure). They turned out to be neglected quite often but are very helpful when it comes to the sensors’ quality assurance. These tests demonstrate whether a sensor is expected to fulfil the high requirements in most of the applications related to “machines” (high-speed train operation, photovoltaic systems, snow making machines and many more). Interestingly enough, that nowadays not many users – even in safety-related installations on airports, for example – have asked their suppliers to show them these test reports.
As we can see, we are more and more surrounded by a high-tech environment. As we need to rely on it, the perfect sensors need to be re-defined for every upcoming requirement – therefore innovative thinking becomes more important than ever before!
The full article can be read in the April 2015 issue of Meteorological Technology International or on Lufft.com.