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D-TEC O
M
PERATOR
S
ANUAL
6.1.1 Electric Field Patterns
As mentioned above, some electric fields can extend a long distance from one side of a power
line and fade abruptly on the other side. In Figure 6-3 below, a common power line configuration
is shown where this type of electric field pattern occurs. Notice that the electric field will extend
only 10 to 20 feet (3 to 6 meters) where two insulators are present but 70 to 80 feet (21 to 24
meters) where there is only one insulator. The operator of the mast and D-TEC may not be able
to raise the mast where the electric field extends this far and may have to move to the other side
of the power line or to a different location.
70-80 FT
10-20 FT
(21-24 m)
(3-6 m)
ELECTRIC FIELD
INSULATORS
ELECTRIC FIELD
TELEPHONE POLE
Figure 6-3 Electric Field Pattern
6.1.2 Electric Fields
An electric field (E-Field) measures the amount of voltage potential in units of kilovolts per meter
(kV/m). When a mast is attached to a vehicle or other object that is in contact with the earth's
surface, the electric field is measured relative to ground. The size of the vehicle and height of
the mast also have an effect on the field strength that is measured by the D-TEC system. The
following illustration shows a perfect electric field compared to an electric field with the presence
of a vehicle and mast (Figure 6-4). Note that the vehicle is at ground potential (0 volts). The
electric field lines cannot pass through the vehicle and must go up and around. The D-TEC
Sensor is negatively affected by its close proximity to the vehicle but as the Sensor is raised into
the air via the mast the electric field collapses about the D-TEC Sensor and a more true reading
is achieved.
6-2
TP-5522901-00
July 2018
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