Balisor is a system of illuminated

beacon A beacon is an intentionally conspicuous device designed to attract attention to a specific location. A common example is the lighthouse, which draws attention to a fixed point that can be used to navigate around obstacles or into port. More mode ...

s for high voltage power lines using a cold-cathode low-pressure

neon lamp A neon lamp (also neon glow lamp) is a miniature gas discharge lamp. The lamp typically consists of a small glass capsule that contains a mixture of neon and Penning mixture, other gases at a low pressure and two electrodes (an anode and a cold ...

,David F. Rider '' Jane's airport equipment fifth edition'', Jane's Pub. Co., 1986 page 92 used as an

aircraft warning light Aviation obstruction lighting is used to enhance the visibility of structures or fixed obstacles which may conflict with the safe navigation of aircraft. Obstruction lighting is commonly installed on towers, buildings, and even fences located i ...

Description

High voltage power cables, particularly those close to

airport An airport is an aerodrome with extended facilities, mostly for commercial air transport. Airports usually consists of a landing area, which comprises an aerially accessible open space including at least one operationally active surface ...

s, need to be visible day and night. During the day, brightly coloured balls positioned along the length of the cables are sufficient, but during the night, lighting is necessary. These beacons provide this lighting by glowing red, the standard colour used in aviation for warning beacons. The system is extremely simple, efficient and reliable and is considered the most economically viable solution. Its working principle is attractive, because it uses a phenomenon usually considered as a weakness. However a large disadvantage is that it does not work when the line is switched off. It cannot also be used on

HVDC A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating curren ...

powerlines, but similar devices may be also used on

mast radiator Mast, MAST or MASt may refer to: Engineering * Mast (sailing), a vertical spar on a sailing ship * Flagmast, a pole for flying a flag * Guyed mast, a structure supported by guy-wires * Mooring mast, a structure for docking an airship * Radio mas ...

Operating principle

The interest of the system lies in the way it obtains a power supply directly from the single cable on which it is mounted. It is difficult to obtain a very small amount of energy from a line which transports an enormous amount. Each high voltage cable creates an electric field around itself, in the same way as any live

electrical conductor In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gener ...

. When the

electric potential The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is defined as the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in ...

of such a cable is sufficiently high, its electric field causes a significant

voltage difference Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...

between the cable and its immediate neighbour. (It is the strength of the

electric field An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...

that makes it difficult to use low powers.) As a result, a second conductor a few metres long, insulated from but parallel to the high voltage cable, will have a potential different from that of the main cable. Together the conductors make a

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

charged across an air gap (

dielectric In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mate ...

). Under certain conditions, the accumulated charge (and hence the potential difference) is sufficient to trigger a

discharge lamp Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionization, ionized gas, a plasma (physics), plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and ...

. This what is used in practice, giving a reliable and robust beacon.

References

External links

{{Portal, Energy, Electronics, Aviation * On th
manufacturer's site
: Obsta
Presentation

Product Range
Aviation safety Electric power transmission systems Signalling lights Warning systems

Description

Operating principle

See also

References

External links