  Digital equipment such as computers, telecommunication systems and
instruments use microprocessors that operate at high frequencies allowing them
to carry out millions or even billions of operations per second. A disturbance
in the electrical supply lasting just a few milliseconds can affect thousands
or millions of basic operations. The result may be malfunctioning and loss of
data with dangerous or costly consequences (e.g. loss of production). That is
why many loads, called sensitive or critical loads, require a supply that is
protected. Many manufacturers of sensitive equipment specify very strict
tolerances, much stricter than those in the distribution system for the supply
of their equipment, one example being Computer Business Equipment Manufacturers
Association for computer equipment against distribution system disturbances.
The design of this uninterrupted power supply (UPS) for personal computer (PC)
is necessitated due to a need for enhanced portability in the design of
personal computer desktop workstations. Apart from its original functionality
as a backup source of power, this design incorporates the unit within the
system unit casing, thereby reducing the number of system components available.
Also, the embedding of this unit removes the untidiness of connecting wires and
makes the whole computer act like a laptop. Not to be left out is the choice of
a microcontroller as an important part of the circuitry. This has eliminated
the weight and space-consuming components that make up an original design. The
singular use of this microcontroller places the UPS under the class of an
advanced technology device.
