This product was designed for the electric utility industry. It allows
them to determine the phase (A, B or C) of an unknown overhead or
underground conductor in a three phase system. It is comprised of three
units; The Reference Unit, the Field Unit, and the Hotstick. The
Reference Unit gets installed (typically at a substation) on a
known-phase conductor (typically phase A). The Field Unit is the yellow
suitcase shown above and it is taken into the field where the
lineman touches the companion Hotstick
unit to an unknown conductor. The
Hotstick sends wireless information to the Field Unit which in turn
communicates with the Reference Unit to display the phase of the probed
The Field and Reference Units both contain GPS receivers which are used
to measure the exact time between the zero-crossings of the AC voltage
waveform. The Reference Unit is connected on a known-phase waveform and
it is compared against the unknown-phase waveform probed by the
Hotstick. The Field and Reference Units employ cellular and landline
modems respectively to exchange the timing information. The system can
display which phase
(A, B or C) is being probed and also the phase angle information (in
degrees) on an LCD screen on the Field Unit.
For safety considerations, the Hotstick is an inherently "ungrounded"
system where the electrical path is completed to earth ground via the
tiny capacitance which exists between the Hotstick enclosure and the
earth. The Hotstick contains microprocessor based auto-ranging circuity
which allows direct contact with voltages from 120V to 365kV.
For more information or to purchase this product contact EDM International, Inc.