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these components to each other. The central computer is a
mainframe type of computer, issuing commands through telephone
lines to substation equipment, and is fully redundant, meaning
that FPL purchased two central computers, one of which was used
and one of which served as a backup. When FPL purchased the
central computer at the beginning of the LMS implementation, the
system could handle 600,000 to 700,000 customer locations
(transponders) and the corresponding substation equipment. When
FPL purchased the central computer it also purchased related
software,45 and its software license was perpetual.
The substation control equipment received commands from the
central computer, translated those commands, and sent the
commands through power lines to transponders in customers’ homes.
Substation control equipment includes the control receiving unit,
the outbound modulation unit, the modulation transformer unit,
the inbound processing unit, and the associated equipment.
Transponders are installed at customers’ homes, the transponders
accept commands that are sent from the substation equipment, and
they act on the commands by turning appliances on or off at
customers’ homes. Although the components of the LMS function in
an integrated manner, each transponder, once installed, was
45 According to a document entitled “SOFTWARE PRODUCTS
LICENSE AGREEMENT”, the software was licensed from A.B. Chance
Load Management Systems (A.B. Chance), effective on Oct. 4, 1985.
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