General Provisions - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 19

Figure 5. Hardware and software of I&C system with distributed structure

The specified peculiarities allowed building
various software-hardware complexes on the
basis of one and the same equipment family for
overall or individual I&C systems, different by a
composition, structure, technical characteristics,
meeting requirements of individual customers, and
at the same time provide rational use of means
and work efficiency during design, programming,
manufacturing and operation of these SHCs.
(This does not exclude a possibility of technically
and economically grounded cases of adopting
individual; purchased items, not included in the
composition of equipment family).
It is appropriate to mention fundamental differ-
ences between the equipment family and SHC. The
equipment family is a conceptual object and exists

documentation, methods, instructions, standards,
etc. The same equipment family generates a set of
various SHCs, where each is a real object (product
of industrial manufacturer). The equipment family
is not bound to any specific system: it is intended
for typical functions, structures, environment,
ways of use and operating conditions, common
for a sufficiently wide, though restricted range of
different systems. Each SHC that can be imple-
mented on the basis of equipment family is usually
devoted to one specific system. Separately taken
SHC uses only a part of possibilities of a relevant
equipment family (restricted nomenclature of
hardware and software, supporting constructions,
signals, interfaces, etc., required and sufficient for
a specific application).