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 power factor meter, a discrete kilowatt-hour meter, a discrete ammeter with associated ammeter
switch, and a discrete voltmeter with associated voltmeter switch. All of these separate meters
can now be replaced by one device, which is no larger than one of the five meters mentioned
above.
Use of microprocessor based controls has also made improvements in controls of complex
packages, such as boilers, gas turbines, compressors and generators. The new control packages
are: smaller, can be readily reprogrammed for changing conditions, and can be a significant
engineering and design cost savings over the old style discrete relay systems used in the past.
Previous control systems were uniquely configured for the requirements of each customer,
allowing no standardization of manufacturing and testing. The new microprocessor based
controls allow the same control system to be supplied for each customer, with only the software
requiring adjustment. The customer benefits because changing site condition problems are
remedied by simply changing the software, rather than making numerous wiring connection
changes that are usually not documented. The microprocessor system can display the new
software configuration on demand, thus eliminating the documentation problem. The low cost of
personal computers and the proliferation of software (for use in almost any application) has
allowed operating and engineering personnel to monitor and control certain operations from their
own office. Laboratories can now run automated tests and have the personal computers monitor
various test parameters and produce automated test reports.
Relatively simple processes can be controlled by a personal computer and modem connected to a
remote location via telephone lines. A simple RTU, located at the other end, can accumulate the
remote data signals and transmit any commands to be executed. Such systems are quite
inexpensive, but must be recognized as less reliable than SCADA or DCS systems due to the
generally non-redundant designs used and the lower cost commercial grade design of personal
computers, which are not specifically designed for 24 hour continuous operation over long time
periods (many months or years). The development of microprocessor based test equipment has
allowed testing to be performed by less skilled personnel, as the knowledge that would have been
required to run the test and interpret results is now programmed into the microprocessor for
certain dedicated testing equipment.
9.3 COGENERATION. Cogeneration is not a new technology. It has received new emphasis,
however, resulting from the increased awareness of the need for energy conservation and from
the regulatory impetus resulting from the 1978 Public Utility Regulatory Policies Act (PURPA).
PURPA requires public utility companies to accept electric power generated by their customers,
if certain basic energy conservation parameters are met. Cogeneration is the useful production of
more than one form of energy in the same plant (e.g., the simultaneous production of process
steam and electricity, the use of waste heat recovery devices to produce electricity from a diesel
for domestic use). Prior to PURPA, even if it were economical for the customer to install
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