Intrinsic safety circuit parameters

Circuit capacitance and inductance, including the values of these parameters for interconnecting wiring, are integral parts of the overall analysis. It is not always possible to assure that the system will be maintained as designed with only approved intrinsically safe components and with circuits of the capacitance and inductance as originally installed. For this reason, intrinsically safe systems are used primarily at locations where there are sufficiently trained personnel to assure that the intrinsic safety of the system is always maintained. 

The parameters relevant to intrinsic safety, no-load voltage and short-circuit current of the stand-alone circuits are Uw and Iscl = Uv, /Ri or U2Q and Isc2 = U2o/R2, respectively. In series connection, itv may exceed the voltage limitation of, e.g., a capacitive circuit. The short-circuit current Isc can be divided into ... 

An electrical component or combination of components of simple construction with well-defined electrical parameters which is compatible with the intrinsic safety of the circuit in which it is used... 

For each interconnection of an intrinsically safe circuit with an associated apparatus a proof of intrinsic safety - i shall be performed on the basis of the safety-related maximum values. As far as the simple standard design given in this example (Fig. 6.218) is concerned, it is assumed that the associated apparatus only - the Ex i-isolator - can feed electrical power into the intrinsically safe circuit. Therefore the safety-related parameters are marked as out-parameters with the subscript o. On the other side, the intrinsically safe apparatus may consume electrical power only. Its values are marked as in-parameters, subscript i. ... 

Low parameters of primary circuit, such as pressure close to the atmospheric and temperature only slightly higher than 100°C secure high reliability, intrinsic safety and ecological compatibility of nuclear district heating plant based on RUTA reactor intended for district heating of settlements. Altogether, these features make it possible to construct such plants in maximum proximity to the consumers. 

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