Wave equations for transmission line impedance and shunt admittance of the line. A 161kv transmission line tripped out of service due to the failure of the lower jumper of a verticallymounted wave trap. The main function of the line trap is to provide a high impedence at powerlinecarrier frequencies. It is common practice to install wave traps at each end of a two terminal line. As this distance is greater than the 100 feet, electric and magnetic field emf calculations have not been estimated. Section 2 the approximate nature of the transmission line equations t. It is a recommended practice to install line traps at all three. A surface wave transmission line this article is the first in a series of qex articles that involve surface wave transmission line theory and applications for use by radio amateurs. Line traps, wave traps, power line carrier, tuning device, main coil. In spite of the growing use of digital communication systems especially those employing optical fibre links for which abb produces a comprehensive line of equipment plc is still often the most cost effective, and reliable, solution to cover the operational needs of a power system. It reduces corona losses in transmission lines in power system. What it does is trapping the high frequency communication signals sent on the line from the remote substation and diverting them to the telecomteleprotection panel in the substation control room through coupling capacitor and lmu. High voltage transmission line are used for the transmission of carrier signals between 30khz to 50khz for speech, data, and protection signals. The wave traps performs the task of directing the carrier energy on the transmission line towards the remote line terminal and not towards the station bus, isolating it from bus impedance variations.
A line trap, also known as wave trap, or highfrequency stopper, is a maintenancefree parallel. The line trap or wave trap prevents unwanted loss of carrier signal power and also prevents carrier signal transmission to adjacent power lines. Wave trap is used to create high impedance to the carrier wave high frequency. The line traps shall be in accordance with the latest edition of iec 60353. The second article describes a new theory for understanding antennas.
It is a parallel tuned circuit comprising of inductance l and capacitance c. Likewise, since the transmission line wave equation is a linear. The third article describes a very wide band antenna. A detailed study on how communication takes place on existing power line. Electromagne2c wavepolariza2on electricandmagne2cwavesareat rightanglestoeachother magne2cwavedissipateswithina fewwavelengthsofantenna. A parallel resonant circuit has high impedance as its.
They are inserted in series in a power transmission line in order to conne the high frequency carrier signal to the appropriate line sections. As you might expect, the voltage and current on a transmission line is determined by the devices attached to. How does the wave trap work at an electrical substation. Temporary ratings the temporary ratings report encompasses rating changes with limited durations, typically less than six months. Ppt on power line carrier communication transmission. The wave trap is usually a form of a parallel resonance circuit, which is tuned to the carries energy frequency. The line trap consists of a series inductance shunted by a. A transmission line may have at its end an impedance, z, which is not equal to the characteristic impedance of the line 2.
All rus borrowers rus electric staff effective date. Line traps shall be inserted into extrahigh voltage transmission line to prevent undue loss of carrier signal for all power system. Power line carrier communication plcc electrical4u. Consider a lossless transmission line with a wave after time t has travelled through a distance x. To sectionalize the transmission network and protect against failures, a wave trap is connected in series with the power transmission line. Consider the semiinfinitely long transmission line shown in figure 2. Wave trap is a parallel tuned inductor capacitor tank circuit made to be resonant at desired communication frequency. General solution of the transmission line, the two standard forms for voltage and current of a line terminated by an impedance, physical significance of the equation and the infinite line, the two standard. Consider the wave travelled a distance dx in a time dt. The reason you need to specify it with the line tuner is so that the line tuner can be pretuned and tested for you in the factory, specifically, the impedance matching transformer part of the tuner.
Wave trap is a basket looking coil having high inductance. Power line carrier communication plcc electrical concepts. Wave divider afc detector agc detector vco 3stage ifamplifier frequency detector and phase detector 9 10 15 7 if agc 12 tuner agc tuner agc takeover point tda9801 video demodulator video amplifier 3 19 8 14 11 buffer amplifier and noise clipper fmpll detector limiter amplifier af amplifier 1 v pp 4 5 6 sound mute switch sound trap. In order to achieve this a reflected wave is formed. Power line carrier equipment plc network power line. Transmission lines signal transmission and reflection. The plcc equipment and wave traps shall be installed at. Line traps are used to prevent the loss of these high frequency signals to the substation side. The wave trap connected in series with the feeder line is a kind of reactor.
Transmission line parameters obtained from text module 2. The wave trap is put in use alongwith a coupling capacitor or a capacitor voltage transformer cvt both of whic. A line trap, also known as wave trap, or highfrequency stopper, is a maintenance free parallel. Ppt on power line carrier communication free download as powerpoint presentation. The vertically mounted wave trap can move excessively in windy conditions and subject the lower jumper to mechanical stress. Thus back up protection is also obtained for the system. Transmission owner to transmission operator top problem statement. Some of the changes corrected errors in the derived. What is a wave trap in a substation and how does it work. Principles of rf and microwave measurements lecture notes and experiments for ecen 46345634 by. Transmission lines basic principles norbert wiener. The details of the transmission line modeling can be found on my website. For a single wave solution in one direction, the ratio vziz is the same everywhere on the line, and is defined as the characteristic impedance z o, which for a lossless line is a real.
Consider the charge between conductors of a line up to a distance x. Line traps are series connected to the transmission lines, and are designed to withstand the rated power frequency current and the shortcircuit current to which the. Line traps are connected in series with hv transmission lines. Resistance along the line r inductance along the line l all. They consist of one or more sections of resonant circuits, which block the high frequency carrier waves 24 khz to 500 khz and. This type of reactor is mainly used to facilitate power line carrier communication. Transmission line theory different types of transmission lines, definition of characteristic impedance, the transmission line as a cascade of tsections, definition of propagation constant. Line traps are cylinderlike structures connected in series with hv transmission lines. Also hybrid relay trip signals can be derived and can ensure complete protection of transmission line. Wave trap is provided in the line after the cvt if we see from transmission line side then cvt will come first and then cvt will come. This bulletin is an update and revision of previous rea bulletin 651, design guide for rural substations revised june 1978.
Transmission line protection based on travelling waves. Thus, a wave on the line faces the dilemma of obeying two difference ohms laws. Line traps are connected in series with the transmission lines. The main function of the line trap is to present a high impedance at the carrier frequency band while introducing negligible impedance at the power frequency. Wave trap is installed in the substation for trapping the. The inductive reactance of the line trap presents a high reactance to highfrequency signals but a low reactance to mains frequency. Travelling wave on transmission line is the voltage current waves which propagate from the source end to the load end during the transient condition.
An electro static flux is associated with the electromagnetic flux and voltage wave with the current wave. These high frequency damages the power system components which are. Thus proposed method is a solution technique for transmission line. There have been two or three major revisions to my mathcad transmission line models in the past couple of years. The high impedance limits the attenuation of the carrier signal within the power system by preventing the carrier signal. This reactor along with the coupling capacitor of the line creates a filter circuit to block the frequencies other than power frequency. You should not include the line trap inductance in the characteristic impedance of the transmission line.