Transmission Line Arrester TLA

Transcription

1 Transmission Line Arrester TLA

2 Introduction Numerous technical publications have stated that lightning is responsible for approximately 65% of all of the non-scheduled outages occurring on transmission lines, thus creating many issues for power supply utilities. Power supply utilities themselves have verified the load losses due to voltage sags on their systems from transitory outages caused by lightning activity and in some regions they have found serious permanent damage caused to the system itself due to these transitory disturbances occurring on important lines. The effect of these transitory disturbances on transmission lines can also be more critical in areas with high ground resistivity when associated with high lightning activity. Although it is a fact that most of the non-scheduled outages are transitory in nature, with a fault time shorter than 1 minute, in many cases this is still deemed, by power supply utilities and their customers, to be unacceptable. This loss of supply is critical for all modern industries now so reliant on sophisticated electronic equipment and especially production processes sensitive to momentary disturbances on the system. In order to reduce the number of non-scheduled outages in electrical systems, power companies and industrial consumers have been studying and promoting improvements to transmission lines thereby increasing their reliability. There are different methods to improve transmission lines performance due to lightning: a) Increase the dry arcing distance from the insulators strings. b) Install shield wires in lines without shield wire. c) Improve the shield wire performance. d) Improve the grounding system performance of surges by improving the tower footing resistance. e) Installation of transmission line arresters to counteract the effects of lightning or switching activity In most cases line arresters (TLA), electrically connected in parallel with the insulator string, have been considered as the most effective method currently applied to improve transmission line performance, especially when associated with improvements to the grounding system and usually presents the best benefit versus cost relationship in reducing flashovers of the insulator string due to excessive voltages. 2

3 TLA Transmission Line Surge Arresters up to 230 Suspension Clamp Utility Utilities are required by demand to increase availability and reliability of transmission systems. Therefore eliminating operational high cost outages and mandoratory penalties is high on the agenda. Key Features HV arrester suspended from a transmission line giving enhanced transmission line performance. Increasing system line voltage on standard insulated transmission lines. Benefits of TLA Applications Grading Ring for voltages above 150 Silicone Rubber Insulation Minimising circuit breaker operation with possible system outage resulting from back flashover on the transmission line. Switching overvoltages are absorbed over the length of the line reducing the severity of surge at the substation. Disconnect Device Transmission systems can be operated even where sub-soil gives poor tower footing resistance. Earth Cable with StrainRelief Eliminating interrupted power supply for sensitive industrial processes. Installing Transmission Line Arresters on a standard 3 phase voltage system along the line, at calculated intervals, allows for optimum performance of the TLA, to give an increased system line voltage. Therefore eliminating the need to increase the standard insulation level required on conventional system upgrade. 3

4 Electrical Performance Specification: Classification: Voltage Rating: High Current Performance: IEC kA 15 to kA Line Discharge Class: 2 Minimum Energy Capability: 4.5kJ/ at Ur according to IEC (Clause table 4 and ) TLA1 TLA2 TLA TLA Disconnect Device tested in accordance with IEC Class2. Insulation Material: Vibration Tested Silicone Rubber Report No. BOE TLA System, Brazil TLA Dimensions TLA4 TLA3 TLA2 A TLA1 A A A 4

5 Protective Characteristics Product Code Rating Voltage Max. cont. operating voltage (COV) Temporary overvoltage capability for 1 sec (TOV) Max Residual voltage crest with current wave Switching surge 30/60 us 125 A 500 A 5 ka Lightning Current 8/20 us 10 ka 20 ka Steep Current Residual Voltage 10 ka Crest TLA1B15L1E1M TLA1B18L1E1M TLA1B21L1E1M TLA1B24L1E1M TLA1B27L1E1M TLA1C30L1E1M TLA1C36L1E1M TLA1C39L1E1M TLA1E42L1E1M TLA1E45L1E1M TLA2C48L1E1M TLA2C60L1E1M TLA2C72L1E1M TLA2C75L1E1M TLA2E84L1E1M TLA2E96L1E1M TLA3C108L1E1M TLA3C120L1E1M TLA3E138L1E1M TLA3E144L1E1M TLA4C150L1E1M TLA4E168L1E1M TLA4E180L1E1M TLA4E192L1E1M

6 Mechanical and Reference Information Total Creepage mm (nom) Overall height mm (max) A Drawing Reference Pivot Suspension Clamp Drawing Reference Disconnect Drawing Reference Strain Relief System Drawing Reference Data Sheet Reference E1 E BOW BOW BOW BOW-EPP-TLA1B BOW BOW BOW BOW-EPP-TLA1B BOW BOW BOW BOW-EPP-TLA1B BOW BOW BOW BOW-EPP-TLA1B BOW BOW BOW BOW-EPP-TLA1B BOW BOW BOW BOW-EPP-TLA1C BOW BOW BOW BOW-EPP-TLA1C BOW BOW BOW BOW-EPP-TLA1C BOW BOW BOW BOW-EPP-TLA1E BOW BOW BOW BOW-EPP-TLA1E BOW BOW BOW BOW-EPP-TLA2C BOW BOW BOW BOW-EPP-TLA2C BOW BOW BOW BOW-EPP-TLA2C BOW BOW BOW BOW-EPP-TLA2C BOW BOW BOW BOW-EPP-TLA2E BOW BOW BOW BOW-EPP-TLA2E BOW BOW BOW BOW-EPP-TLA3C BOW BOW BOW BOW-EPP-TLA3C BOW BOW BOW BOW-EPP-TLA3E BOW BOW BOW BOW-EPP-TLA3E BOW BOW BOW BOW-EPP-TLA4C BOW BOW BOW BOW-EPP-TLA4E BOW BOW BOW BOW-EPP-TLA4E BOW BOW BOW BOW-EPP-TLA4E-192 6

7 Accessories TLA Pivot Suspension Clamp Suspension Clamp Assembly Galvanised Steel Clamp Straps & Fixings Aluminium Line Clamp Copper Shorting Braid / Cable Galvanised Steel Line palm M16 x 35 Min. Full Thread M12 Connection For Shorting Braid / Cable TLASurge Arrester Clamp Conductor Dimensions mm U Bolt Weight Range Dia. A B C D Torque L mm Nm 1.8 kgs L mm Nm 3.0 kgs L mm Nm 4.3 kgs L mm Nm 6.0 kgs Earthing Configuration TLA Disconnect - E1 TLA Strain Relief System - E2 TLA Surge Arrester TLA Surge Arrester Disconnect Device Earth Connection Disconnect Device Earth Connection Strain Relief Shackle and Swivel Joint 7 Strain Relief Wire Connection

8 Performance Improving the reliability of a 69 transmission line effected by lightning. Individual Towers Protected with TLA Probability of flashover Tower Numbers Actual without TLA 1 TLA per circuit 2 TLA s per circuit Installing one TLA on an individual tower reduces the probability of flashover. If you take a look at (tower 35) which has an 80% probability of flashover, this can be reduced to less than 60% with one TLA installed on the bottom phase. If a second TLA is installed the reduction in probability is minimal. Typical Transmission Line 69 Adjacent Towers Protected With TLA Probability of flashover Tower Numbers Actual without TLA 1 TLA per circuit 2 TLA s per circuit Installation of additional TLA s on adjacent towers reduces the probability of flashover on (tower 35) to less than 30% and then if you install a further TLA on (tower 35) again the probability of flashover is reduced to less than 20%. 8

9 Tower installations Tower The number of the TLA installed on the tower depends basically on the tower geometry and configuration as well as the earthing transient impedance behaviour. Insulator Line For towers with a horizontal conductor configuration, conductors in a single line across the tower, normal practice is to install a TLA on both of the two outside phase conductors. Lead Earth Tower TLA Disconnect Device Insulator For towers with a vertical conductor configuration, conductors arranged above each other, the resultant transient voltage across the insulators string sets is usually higher at the bottom phase, which presents a lower distance to the soil and lowest coupling with the shield wire. Therefore, transmission lines with a vertical configuration and low tower footing impedance, only one TLA is necessary to install on the bottom phase, but for higher impedances it might be necessary install two and sometimes three TLA s. Line Lead Earth TLA Disconnect Device A direct lightning strike to the transmission line without a shield wire will cause the discharge current i(t) to divide into two current waves travelling on the both directions down the line with magnitude of i( t ) / 2 (it is valid when we consider the impedance of the discharge channel as infinite). This current therefore produces a voltage wave v (t) in both directions which considering as a first approach that the transmission line is without losses and distortions, results in a voltage along the line which can be estimated by: Tower V ( t ) = Z0. i ( t ) / 2 Insulator Line TLA For lines with shield wires, the voltage on the top of the tower will be significantly lower and will depend on the lightning striking point, the tower impedance and mainly of the earthing transient behaviour. Disconnect Device Earth Lead 9

10 The SPG1 Spark Gap is designed for use with traction circuits to provide virtually instantaneous protection of both equipment and personnel from power system faults. The unit also provides protection against lightning generated voltages which would otherwise cause damage to signalling and cable circuits. The SPG1 is constructed in stainless steel of rugged design allowing the SPG to be installed in harsh environments such as track side locations without additional weather protection. Suitable for use on circuits where standing/induced voltages do not exceed 110v RMS. Fast operation Typical 5 microsecondswith 1kA fault current. Internal spark gap module unit easily replaced after fault current operation. Fail safe feature ensures safety to personnel and equipment. Service proven performance. High internalimpedance with low capacitance does not interfere with track signalling circuits. The Bowthorpe EMP range of Surge Arrester monitoring instruments are fully tested for use with any manufacturers surge arrester. The SC12 is a Surge Counter only, whilst the SC13 provides the additional measurement of total leakage current. The analogue instrument provides a means of monitoring the current through the arrester and the leakage current over the surface of the arrester housing. Significant changes after installation may indicate a deterioration in the arrester or a build up of surface contamination. These instruments, which require no auxiliary supply, are designed for installation in the earth connections of a single surge arrester or alternatively the SC12 may be used with the common earth of a three phase set. Fully weatherproofed and sealed for life they are housed in a one piece gravity die cast aluminium case coated to enhance its already high degree of resistance to surface providing a single clearance hole for corrosion. The glass viewing the galvanised steel M12 bolt window is sealed in place, using a supplied. silicon rubber adhesive, and a desiccator is enclosed to ensure any The SC12 and SC13 are service residual moisture trapped during proven and require no special sealing is absorbed for the service maintenance or servicing apart from life of the counter. Mounting is general cleaning of the glass effected by means of an integrally viewing window and the moulded cast lug at the rear of the case epoxy resin line terminal bushing. Additional Product Lines: Energy Division Transmission Surge Arresters Polymeric DC Traction Surge Arrester SparkGap TypeSPG1 Transmission Surge Arrestres Modular Single Column Polymeric Surge Arrester Modular Series Parallel Polymeric Surge Arrester Polymeric Housed Surge Arrester Porcelain Housed Surge Arrester Polymeric DC Traction Surge Arresters Rolling Stock Track Side Spark Gap Type SPG1 Protection between overhead catenary structure earth and system earth Protection of single bonded power cable circuits Protection of low voltage DC power supplies Protection of cathodic protection power supplies. Safety, Connectors and Earthing Equipment Surge Counters Type SC12 & SC13 Safety, Connectors and Earthing Equipment. Portable Earth Kits Insulated Poles Pole Heads Earthing Clamps Line Taps and Shrouds Cable Spiker Airfield Lighting Box Type 2DCAFL4 Protection of airfield lighting control equipment. Surge Counters Type SC12 & SC13 Used in series with HV Surge Arrester SC12 Surge Counter SC13 Combined Surge Counter with Leakage Current Meter For further information contact hvsurgearresters@tycoelectronics.com All of the above information, including drawings, illustrations and graphic designs, reflects our present understanding and is to the best of our knowledge and belief correct and reliable. Users, however, should independently evaluate the suitability of each product for the desired application. Under no circumstances does this constitute an assurance of any particular quality or performance. Such an assurance is only provided in the context of our product specifications or explicit contractual arrangements. Our liability for these products is set forth in our standard terms - conditions of sale. ALR, AMP, AXICOM, B&H, BOWTHORPE EMP, CROMPTON INSTRUMENTS, DORMAN SMITH, DULMISON, GURO, HELLSTERN, LA PRAIRIE, MORLYNN, RAYCHEM, and SIMEL are trademarks. Energy Division a pioneer in the development of economical solutions for the electrical power industry. Our product range includes: cable accessories, connectors & fittings, electrical equipment, instruments, lighting controls, insulators & insulation enhancement and surge arresters. For more information and your country contact person, please visit us at: Tyco Electronics Bowthorpe EMP Stevenson Road, Brighton, East Sussex, England BN2 0DF Phone: +44 (0) , Fax: +44 (0) BOW-EPP Tyco Electronics Raychem GmbH, Energy Division Finsinger Feld 1, Ottobrunn/Munich, Germany Phone: , Fax: