VAWTs can rotate at different rotational speeds depending on the wind conditions. Even the well-designed ones that are protected from vibration avoid excessive vibration at resonance frequencies. Typically this behavior has high amplitudes and can auto-amplify. Resonance leads to deflection on the wind blades that can drastically reduce turbine life. Traditional vibration monitoring solutions are not adapted for this application since they generate false alarms and stop the turbine every time vibration on the mast is high. These false alarms lead to reduction of energy generation and turbine efficiency. For these applications, detection of resonance is a must and only then is alarm and action is required. For this application, Sequoia developed the SeTAC W2T. The W2T is a smart and inexpensive device developed to work in external environment (under raining and lighting environments), and able to simultaneously check the vibration on two axes and to stop the turbine only when resonance vibration is detected.