Abstract: A current transformer (5) having a plurality of primary and secondary windings, comprising a top Strain measuring system of wind turbine blades (11) during the performance of static tests that comprises an equipment for measuring the strain at multiple locations in mono-mode optical fibers (5, 7, 9) using Rayleigh scattered light, that includes an OBR interrogator (23), an interface device (25) and an Acquisition System (27), said mono-mode optical fibers (5, 7, 9) being attached to the blade (11) subjected to said tests for obtaining high spatial resolution measurements of the blade strain during said tests. Said optical fibers (5, 7, 9) may be placed whether in a longitudinal direction or in a non-longitudinal direction or in a non-linear shape in given blade sections and may be bonded whether to the outer skin (31) of the blade (11), or into grooves (51, 53) in the outer skin (31) of the blade (11) or embedded between two structural laminates (33, 35) of the blade (11).

Abstract: A current transformer (5) having a plurality of primary and secondary windings, comprising a top Strain measuring system of wind turbine blades (11) during the performance of static tests that comprises an equipment for measuring the strain at multiple locations in mono-mode optical fibres (5, 7, 9) using Rayleigh scattered light, that includes an OBR interrogator (23), an interface device (25) and an Acquisition System (27), said mono-mode optical fibres (5, 7, 9) being attached to the blade (11) subjected to said tests for obtaining high spatial resolution measurements of the blade strain during said tests. Said optical fibres (5, 7, 9) may be placed whether in a longitudinal direction or in a non-longitudinal direction or in a non-linear shape in given blade sections and may be bonded whether to the outer skin (31) of the blade (11), or into grooves (51, 53) in the outer skin (31) of the blade (11) or embedded between two structural laminates (33, 35) of the blade (11).