What is stringing in transmission line?
The stringing blocks, when suspended on the transmission structure for sagging, shall be so adjusted that the conductor on the travellers will be at the same height as the suspension clamp to which it is secured. At sharp vertical angles the sags and tension shall be checked on both sides of the angle.
What are the 4 basic parameters of transmission line?
The transmission line has mainly four parameters, resistance, inductance, capacitance and shunt conductance. These parameters are uniformly distributed along the line.
What is the role of transmission line?
The term Transmission Lines broadly refers to overhead transmission lines and underground cables. The key function of a transmission line is to transfer bulk power between generation sources and load centres.
What is the main reason for SAG in the transmission line?
The lines are often heavily loaded because of increased power consumption, and the conductors, which are generally made of copper or aluminum, expand when heated. That expansion increases the slack between transmission line structures, causing them to sag.
What is a stringing chart?
Stringing chart gives the data per sag to be allowed and the tension to be allowed for a particular temperature. Stringing chart prepared by calculating the sag and tension on the conductor under worst conditions such as maximum wind pressure and minimum temperature by assuming a suitable safety factor.
How do you know if a transmission line is sag?
Calculation of Sag:
- Case1: When the conductor supports are at equal level.
- Sag = WL2/8T.
- Case2: When the conductor supports are at unequal level.
- Sag = WtL2/2T.
What are the three types of transmission line?
Types of transmission line include parallel line (ladder line, twisted pair), coaxial cable, and planar transmission lines such as stripline and microstrip. The higher the frequency of electromagnetic waves moving through a given cable or medium, the shorter the wavelength of the waves.
What is string efficiency?
The string efficiency is defined as the ratio of voltage across the string to the product of the number of strings and the voltage across the unit adjacent string. String efficiency = (conductor voltage)/(number of discs × voltage across the disc nearest to the conductor)
What is Corona in transmission line?
DEFINITION: The ionization of air surrounding the high voltage transmission lines causing the conductors to glow, producing a hissing noise, is called Corona Discharge or Corona Effect.
What are the different types of transmission line?
How do you prevent a sag in a transmission line?
Present techniques to compensate for such sag caused by undesired increase in length of a cable include:
- (i) Shortening the distance between adjacent towers to reduce span length and thus reduce line sag; this is shown in FIG.
- (ii) Erecting taller transmission towers to accommodate line sag; this is shown in FIG.
How to adjust the stringing blocks of a transmission line?
The stringing blocks, when suspended on the transmission structure for sagging, shall be so adjusted that the conductor on the travellers will be at the same height as the suspension clamp to which it is secured. At sharp vertical angles the sags and tension shall be checked on both sides of the angle.
What is stringing overhead conductors in transmission?
Stringing overhead conductors in transmission is a very specialized type of construction requiring years of experience, as well as equipment and tools that have been designed, tried, and proven to do the work.
Why do we need a running board on transmission lines?
The running board makes this possible. Because of the extra high tension required in transmission line construction, steel pulling lines and pilot lines are most practical to use. Torque-resistant, stranded, and swagged cable are used so that ball bearing swivels can be utilized to prevent torque buildup from being transferred to the conductor.
How to install overhead transmission conductors?
There are four methods that can be used to install overhead transmission conductors: 1 Slack stringing 2 Semi-tension stringing 3 Full-tension stringing 4 Helicopter stringing