Methodology for managing traceability in the measurement of torque in wind generators

The research described within this paper has aimed to develop new methods for determining torque in an accurate, traceable way. The proposed methods must suit the operating conditions on nacelle test benches, which are facilities where wind turbines are tested. The operating conditions in these facilities are quite different from the standard machines used to calibrate torque. Normal torque calibrations are performed in static standard machines, while nacelles are tested under rotation. As a consequence, the new proposed methods must operate under dynamic conditions. Therefore, different approaches have been studied, each of them based on different techniques: small scale investigations, new torque transfer standards, etc. All these studies aimed to estimate the performance of the new methods and their associated uncertainties. This article specially describes the force lever system, a new torque transfer standard developed within this research. This new system will not only ensure torque traceability by means of direct mechanical measurements, but also will provide a new way of obtaining torque measurements with a much lower uncertainty than current employed methods.