The present technique provides for the use of spectroscopic probes, such as Raman probes, within the conduits of a polyolefin production system. The hydraulic control system includes a line pressure control device for regulating a variable hydraulic line pressure from a maximum line pressure to a fixed fluid line pressure that is lower than the maximum line pressure when an overdrive clutch is applied in a high gear. The drift region is operated with a floating potential said iT-FET device achieving a self-termination.