Patent ID: 6800867
Filing Date: 2004-10-05
Classification: G01D

Abstract:
A system for measuring a parameter inside an adverse environment that is susceptible to a combustible reaction from dangerous electrical threats received over an electrical conductor from an environment outside of said adverse environment, said system comprising:a sensor disposed inside said adverse environment for measuring said parameter and generating an electrical analog signal representative of said measurement over said electrical conductor; electrical circuitry disposed in said outside environment for receiving said electrical analog measurement signal from said sensor over said electrical conductor; an active safety barrier circuit disposed in series with the electrical conductor at the barrier between the adverse environment and the outside environment for passing said electrical analog measurement signal from the sensor to the electrical circuitry over the electrical conductor while preventing potentially dangerous electrical threats from entering the adverse environment over said electrical conductor, said safety barrier circuit comprising: an analog-to-digital converter circuit for converting sequential time samples of said analog measurement signal to a train of electrical multiple bit digitally coded words representative thereof, said electrical digitally coded words of said train being output sequentially from said analog-to-digital converter circuit; an optical isolator coupled to the analog-to-digital converter circuit for converting the electrical digitally coded words output therefrom into light signals representative thereof which are passed across an electrically non-conductive barrier, and for reconverting said light signals back into the electrical multiple bit digitally coded words after crossing said non-conductive barrier, said reconverted electrical digitally coded words being output sequentially from said optical isolator, said non-conductive barrier for preventing potentially dangerous electrical threats from entering the adverse environment over said electrical conductor; and a digital-to-analog converter circuit coupled to the optical isolator for reconstructing said analog measurement signal from the reconverted electrical multiple bit digitally coded words being received sequentially from the optical isolator, said reconstructed analog measurement signal being passed from the digital-to-analog converter circuit to the electrical circuitry at the outside environment over the electrical conductor.