Wood pylon
Undergrowth masts all forms wooden constructions are summarized primarily serving the electric current conduction or as carriers of communication lines. Furthermore, wooden poles come but also in shipbuilding ( Bemastungsholz ) and as lighting masts used. Is used as a rule a straight grown and healthy trunk of pine, spruce Douglas fir, larch or fir wood. This is placed in the production process by peeling the desired nearly round shape and then impregnated. The maximum height of wooden poles is due to the limited height growth of trees at about 30 meters.
- 4.1 life
Dimensions
The dimensions of wooden poles vary depending on the application and use. The length dimensions are 7-16 m. In the low voltage line, which is the vast majority of wood poles, the pole length is between 9 and 10 m. The length dimensions in the medium voltage range within the interval 11-12 m. The diameter of the mast base is located in the interval 13-33 cm and takes into a plait down from 10 to 22 cm. However, these dimensions are dependent on the length of the poles. For communication masts, the length is 7 to 8 m. To ensure the stability of transmission towers, the minimum diameter of the braid and the strain the foot are required. The DIN 48350 writes the wooden poles to according to their length, foot and Zopfmaßen different " nominal size". The maximum distance between the masts in Germany is 160 meters.
Designs
In the construction of masts for conducting electrical current, there are different variants. It is in the medium voltage range mainly the triangular arrangement of the insulators in use, while for low-voltage line mainly the offset insulator installation will be used. In principle, the construction of wooden poles into two types can be distinguished. There is a pole with supporting insulators and on the other pylons are used with chain insulators. Basic design of wooden mast assemblies are single mast, double mast, mast strut and A- mast. For Kabelendmaste and usually as credit booms in the so-called A- line masts are used. Double masts are used for minor angles in the course of the line, as these higher forces are capable of accommodating as single poles.
Double mast
The double mast consists of two parallel and with little space ( eg 5 cm) arranged Simple masts. The masts are made of bolts and spacers usually made of galvanized steel, joined together.
Longwall mast
Longwall masts consist of a vertical mast on which eg 1.5 meters in depth a tilted mast was been mounted. This mast is to absorb the horizontal forces in an oblique or Finishing Move
A mast
A- masts consist of two inclined mast elements that meet the top and are connected at half the height again by a cross of wood, thus resulting in the shape of a large A. You can absorb high forces in the direction of the two oblique elements.
A- masts are assembled from two simple poles at the site. The poles are top with a bolt and a steel element with claws, which prevents shifting, screwed and in about three meters deep with a tie, eg a steel pipe with welded brackets mounted. In the pipe also runs a 1.5 -meter-long bolts. Under the ground, the two poles are again with two pieces of wood - degraded wooden poles are normally used for this purpose in good condition - frictionally connected by bolts.
Use and displacement
The use of wood as a structural element for poles offers a variety of advantages. Thus wood next to its low investment price and low weight, easy Besteigbarkeit, a high insulating, which is of particular importance in power lines, and a high elasticity. Furthermore, the transport costs are low ( low weight ), and the installation and removal costs are time-saving and cost-effective. The use of wooden poles takes place mainly in the field of low voltage line 110-950 V and for medium voltage cables 5-30 kV, in the U.S. are even wooden poles for 345- kV lines are used. The use of wood poles for power transmission lines is, however, rather rare. However, are the wooden poles, as a carrier of power lines in strong competition with steel and concrete pole and are largely superseded by this. Furthermore, wooden poles are used for the management of communications. However, the need for communication lines on wooden poles increases as a result of displacement by underground cabling systems greatly. Occasionally, and wooden poles were used as antenna support. Because of the limited maximum height, the application is limited to low structures such as radial masts of umbrella antennas, masts supporting reuse of antennas for shortwave, support pole as a transmitting antenna for NDBs or as a support mast for TV and FM low-power transmitters. The use of ships' masts and light towers now play only a minor role. The wooden pole number used in Germany is 3 to 4 million.
Protective treatment
This wooden poles have a long life as possible and remain competitive with other low-maintenance Substitutrohstoffen, a sufficient antifouling technical treatment is necessary. To protect stability loss of the wooden poles especially against biodegradation by fungi, the poles are treated with preservative chemicals. The toxic ingredients of wood preservatives minimize the vulnerability of wooden poles against attack by fungi. This is done by impregnation with Steinkohlenteeröle or by impregnation with biocidal protection salts under pressure impregnation. The requirement for impregnation is the removal of bark and phloem. This processing step is referred to as white shakes. The disadvantage of tar oils are the high environmental and health- damaging aspects, hence the use of creosote in Germany is severely limited. The largest share in the protection of salts take a while copper salts. Especially with timber components with direct ground contact copper salts are used because they have a toxic effect on soft-rot fungi. In order to prevent and combat also copper- tolerant brown rot fungi can, copper salts were previously combined by additives with arsenic, fluoride salts and later with boron salts. However, these are replaced today due to the harmful effects on health and the environment by other additives. Among the most important copper preparations include, inter alia, triazoles, and copper HDO, which act both against soft - as well as against brown and white rot.
Life
The life expectancy of impregnated wooden poles depends on the wood preservatives used. But can be greatly influenced the life also by other factors such as storage time prior to installation, location, quality of the wood and assembly factors used. In the impregnation salts having a protection time of 20 to 30 years is calculated, while if treatment a lifetime of 40 years can be achieved with Steinkohleteerölen. This contrasts with untreated poles, which have an average life of 7 years. For economic reasons, the use of wooden poles is profitable, early failures are to be avoided in the first 10 to 20 years. In addition, a long life expectancy and life is also a guarantor of the form long-term to ensure the traffic safety of wooden poles.
Corolle
Corolle is the name for a pylon type of laminated wood with three runners. The pylon corolla consists of laminated pine. What makes the corolla - wood mast is that it is suitable for cables of higher voltages than normal wooden poles. However, the mast is very expensive and complex processing.
Truss structures
Also in Russia proper lattice towers were made of wood before the 2nd World War for lines with operating voltages of 100 kV erected occasionally