modified/upgraded to detect fraud. This system was developed
in the LETD (Transmission and Distribution Research
Laboratory) at Fluminense Federal University (UFF) and
was supported by the regional electric utility company,
where some regular testing equipment was changed to
avoid current meters in low-voltage commercial consumer
installations. This system does not consider special energy
quality analyses, but an interesting system considering this
specific measurement is presented in [22].
The methodology adopted for identifying fraud is to
measure and compares the electrical current in the client
connection (before and after the individual meter is taken).
The measurement difference, if any, is evidence of fraud via
illegal, electric power connections. To support the fraud
identification, the instrument that is developed and
described in this text has three modules: the first module,
or local unit, is a type of ammeter-clamp, affixed to the tip
of a stick, which measures the current in the client connection.
The clamp or current ‘‘grab’’ is opened through a
mechanism developed especially for this purpose, and it
is manipulated by the operator from the base of the stick.
The current measured by the local unit is transmitted to
a receiver unit located at the base of the stick, which can
give the current reading measured by the local unit, using
an optical interface via a plastic optical fiber [14]; the base
of the stick also contains the opening mechanism of the
clamp. The second module or remote unit is responsible
for the client circuit current measurement (after the
meter). The current measured by the remote unit is transmitted
through a communication interface for radio
frequency (RF) to a receiver unit. The frequency used was
433 MHz because it is an open air frequency and does
not need licensing. The receiver unit is the third module.
The receiver unit measurements taken at the local unit
and remote unit are read and compared. The local unit current
measurement is transmitted to the receiver unit via an
optical interface using a plastic optical fiber. Already the
current measured by the remote unit is transmitted to
the receiver unit via radio frequency. The absolute and percentage
difference is shown on the receiving unit in a
liquid crystal display. If there is a difference, this denotes
fraud. Information about some basic features of the instruments
used in this project adaptation can be found in the
Refs. [23,24].
A preliminary prototype was built and tested in the
field with electric utility company workers that supported
the equipment development herein. The tests were considered
satisfactory, and the equipment proved to be practical,
with only minor changes necessary in the final product.