FRS Free-Run Speed Sensor is designed for applications where
it is necessary to acquire speed readings that are unaffected
by drag load. Before connecting a motor to the dynamometer,
the free-run speed can be obtained from the FRS Sensor. With
its reflective sensor, the FRS does not need to be attached
to the motor but only placed close to the motor shaft (as shown in the photo
to the right). For best contrast, the shaft should be marked with reflective tape.
The sensing end of the fiber optic assembly emits and receives
light reflected from the shaft, and sends the speed signal
to the fiber optic sensor. The raw speed data is then transmitted to either a Magtrol 3411 Torque Display or DSP7000 Dynamometer Controller where it is converted and displayed in rpm.