Located within the variable pitch controller enclosure up-tower, is a Non-volatile Over Speed (NOS) circuit board. This board is designed to feather the turbine during a power outage if the turbine achieves an over-speed condition at the hub. It is also designed to signal the down-tower Winteligence controller that the hub tachometer system used on the NOS board is functioning through a direct hardwire connection to the down-tower Winteligence Relay Input Control Board #2 (ICB 2). A series of problems with these boards has developed over the past 15 years since their manufacturing, including failure of the down-tower signaling transistors, obsolesces of the NOS board processor, and the degradation of the main energy storage capacitor.
Re Nu Controls developed a revised NOS board, designed to tackle all of the problems noted above...LEARN MORE