What does a pile of sugar beets 1,100 feet long, 240 feet wide, 30 feet tall and 242 x 7.5 hp fan motors have in common?
They are actually part of an engineered process where at the end of harvest season the beets are fashioned into a geometric shape (also called a clamp). The fans pump air into the piles from the sides in an attempt to lower the temperature of the mass of beets rapidly. This is done in northern climates in states such as Wisconsin, Minnesota, Michigan and North Dakota at many hundreds of locations.
Sugar beet pile fan control using wireless temperature sensor network
This process starts in early October with the onset of sub-freezing temperatures often enjoyed by the residents of these areas. The beet piles are maintained at below freezing temperatures until March when the piles are recovered and then sent on to processing facilities.
The problems that were inherent with controlling those fans and the 1,364 KW of power input associated with a single pile was monitoring the core temperature of the material and managing that process efficiently.
System integrator Kahler Automation has had many years to look at the problem in concert with their client companies. They had previously tried wired sensor networks which used to be the conventional approach. But that posed another problem. What goes along with sub-freezing temperatures is snow accumulation. Snow has to be cleared off the tops of the piles with snow blowers, to allow for the crucial process airflow through the piles.
That meant that the wired sensors had to be removed periodically to allow the snow removal process to take place. In other words: An awful lot of labor dollars expended each year.
Spinwave Systems introduced an alternative method to Kahler by providing that sensor input without the need of having to remove the temperature sensors multiple times every winter season.
Each of three test piles were designed to have 27 to 39 wireless temperature sensors each in rows of three, perpendicular to the long axis of the piles. The A3 wireless sensor networks easily covered the large area. There are a total of 7 piles at this particular customer site.
Kahler fabricated custom enclosures in which the A3 transceivers and temperature probes are housed and added several features that will further save labor to the overall process. They added a “Tilt Switch” to the battery circuit which, when the Sensor is removed for storage during the spring and summer seasons, will disconnect power to the sensor without having to physically disassemble the package. This also prolongs battery life for several season cycles.
One on line web-based training session was all the crew at Kahler needed to enter the world of wireless applications and streamline a previously labor intensive process.
