A power supply system can include a primary power supply coupled to an output, and a secondary power supply coupled to the output. The first and second elongated members are flexible shafts. The scanning unit is configured to optically scan the reflection measuring graduation by beams of light emitted from the light source passing through the transmission grating and then striking the reflection measuring graduation, from where the beams of light are reflected back toward the detector, which is configured to generate rotation-dependent position signals. An insert is inserted into the openings of the heat dissipating pieces positioned in a series and secured therein.