Balisor
Encyclopedia
Balisor is a system of illuminated beacon
s for high voltage power lines using a cold-cathode low-pressure neon lamp
.
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 which emit a red glow (the standard colour used in aviation for warning beacons) are used to provide this lighting.
The system is extremely simple, efficient and reliable and is considered the most economically viable solution. Technically, its working principle is also very attractive because it uses a phenomenon usually considered as a weakness.
However a large disadvantage of it is, that it does not work when the line is switched-off. It cannot also be used on HVDC-powerlines, but similar devices may be also used on mast radiator
s.
Each high voltage cable creates an electric field around itself, in the same way as any live electrical conductor
. When the electric potential
of such a cable is sufficiently high, its electric field causes a significant voltage difference between the cable and its immediate neighbour. (It is the strength of the electric field
that makes it difficult 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
charged across an air gap (dielectric
).
Under certain conditions, the accumulated charge (and hence the potential difference) is sufficient to trigger a discharge lamp. This what is used in practice, giving a reliable and robust beacon.
Beacon
A beacon is an intentionally conspicuous device designed to attract attention to a specific location.Beacons can also be combined with semaphoric or other indicators to provide important information, such as the status of an airport, by the colour and rotational pattern of its airport beacon, or of...
s for high voltage power lines using a cold-cathode low-pressure neon lamp
Neon lamp
A neon lamp is a miniature gas discharge lamp that typically contains neon gas at a low pressure in a glass capsule. Only a thin region adjacent to the electrodes glows in these lamps, which distinguishes them from the much longer and brighter neon tubes used for signage...
.
Description
High voltage power cables, particularly those close to airportAirport
An airport is a location where aircraft such as fixed-wing aircraft, helicopters, and blimps take off and land. Aircraft may be stored or maintained at an airport...
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 which emit a red glow (the standard colour used in aviation for warning beacons) are used to provide this lighting.
The system is extremely simple, efficient and reliable and is considered the most economically viable solution. Technically, its working principle is also very attractive because it uses a phenomenon usually considered as a weakness.
However a large disadvantage of it is, that it does not work when the line is switched-off. It cannot also be used on HVDC-powerlines, but similar devices may be also used on mast radiator
Mast radiator
A mast radiator is a radio mast or tower in which the whole structure itself functions as an antenna. This design is commonly used for transmitting antennas operating at low frequencies, in the VLF, LF and MF ranges, in particular those used for AM broadcasting. The metal mast is electrically...
s.
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, however, 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
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...
. When the electric potential
Electric potential
In classical electromagnetism, the electric potential at a point within a defined space is equal to the electric potential energy at that location divided by the charge there...
of such a cable is sufficiently high, its electric field causes a significant voltage difference between the cable and its immediate neighbour. (It is the strength of the electric field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
that makes it difficult use low powers.)
As a result, a second conductor
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...
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
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
charged across an air gap (dielectric
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...
).
Under certain conditions, the accumulated charge (and hence the potential difference) is sufficient to trigger a discharge lamp. This what is used in practice, giving a reliable and robust beacon.
External links
- On the manufacturer's site : Obsta