Abstract: A differential pressure cutout switch including a low pressure operating point assembly and a high pressure operating point assembly which are mechanically linked and are operable to respond to first and second pressures supplied over respective first and second pressure inlets of the switch to control a contactor switch assembly which is movable to a first position to provide an open circuit between outputs of the switch and movable to a second position to connect a resistance of a finite value between the outputs as a function of the difference between the two pressures. The differential pressure cutout switch is described with reference to an application in a protection control system for monitoring lubrication oil pressure for a compressor of a refrigeration system.