Overhead Line Engineer Job Description

Trams and trolleybuse with multiple overhead lines

The pantograph causes mechanical oscillations in the wire and the wave must travel faster than the train to avoid causing standing waves that would cause wire breakage. Waves travel faster and the line is tighter. The overhead line is broken into sections to allow maintenance to be done without having to turn off the entire system.

Sections correspond with tension lengths. The section break is a transition from section to section that is set up so that the vehicle's pantograph is in constant contact with one wire or the other. A neutral section is a section of the grid that is insulated and has a short section of line.

The level of safety is increased by the neutral section being earthed. The earthed section in the middle is there to make sure that the transformer controlled apparatus fails and the driver fails to shut off power, so that the energy in the pantograph as it passes to the neutral section is conducted to earth. Sometimes gaps can be found in the overhead lines when changing from one voltage to another or to provide clearance for ships at the bridge.

Electric trains travel across the gaps. Before reaching the gap, power must be turned off and the pantograph lowered. At the crossing between Viale Nomentana and Viale Regina Margherita, there are tram and trolleybus lines.

The crossing is not typical. When high voltages are used or trains run through points at high speed, systems with multiple overhead lines are impractical because of the high risk of short circuits at switches. The Sihltal Zrich Uetliberg Bahn has two lines.

Overhead Electrical Power Lines

An overhead electrical power line is a structure and its use for electric power transmission and distribution system and it is used to transmit electrical energy or power for large distances from the generation center or plant. Distribution lines can be found along streets, alleys, the woods and in backyards. Electric overhead lines are exposed to a lot of things, including wind and lightning.

Electric overhead constructions come in a variety of configurations. One primary circuit is used per pole but utilities sometimes run more than one circuit per structure. The horizontal layout with an 8 or 10 ft wooden crossarm is the most common structure for a typical three-phase circuit.

Overhead Power Lines

Overhead lines have different shapes depending on the type of line. Wood poles set in the earth may be used as a simple structure, or it may be anarmless construction with conductors supported on the side of the pole. In urban areas, the poles are usually tubular steel.

High-voltage lines are often carried on steel towers. Helicopters may be used to place aluminum towers in remote areas. A grounded wire is strung along the top of the towers to protect them from lightning.

An optical ground wire has embedded optical fibers. Overhead wire markers can be mounted on the ground wire to meet the recommendations of the International Civil Aviation Organization. A transmission line has two circuits.

Each tower supports and insulates six conductors. Four conductors are used for single phase AC-power lines. Both circuits operate at the same voltages.

In Germany, most power lines with voltages above 100 kV are implemented as double, quadruple or even a single line. Sometimes all conductors are installed with the help of the pylons. Double circuit transmission lines are not as easy to maintain as single circuit lines because of the proximity of high voltage or switch-off of two circuits.