... high-reliable sensors to check wind speed, wind direction,temperature.PRM,voltage and current3.RPM check and control to protect the blade ... voltage reaching 900VDC to avoid damage of controller, when under high voltage.Wind Generator SZ3K-20KW Controller TECHNOLOGY SPECS ... indoors, brake state (on/off ), dogvane state, cycle of twisting Cable, anemoscope state, and relay state.Anti-twisted function ...