#In line fuse series

2: 138 kV strut arrester assemblies mounted on 138 kV line in U.S. 1: Schematic of 138 kV strut arrester assemblyДЇig. Function of vibration dampers and other motion control devices are also not affected by this arrester configuration.ДЇig. Moreover, it would also not affect line clearances and thermal ratings. If the arrester base becomes pinned, its mass does not have much impact on tension equalization among spans. This same type of arrester strut configuration could also be used in a braced post design provided that mechanical and electrical failure modes are coordinated. As such, this was an early example of an externally gapped line arrester (EGLA) as now defined in IEC 60099 Part 8.

#In line fuse series

The 457 mm (18вЂќ) series ring gap provided electrical isolation from normal AC line voltage and switching surges and connected the MOV elements across the insulator only when lightning overvoltage exceeded 500 kV. At the same time, it did not interfere with function of the double sets of Aeolian vibration dampers. Since this design was rated for 89 kN (20,000 lb) tension and similar load in compression, it satisfied mechanical requirements for lateral restraint. The TLSAs in this case were attached directly to the conductor clamps (see Fig. Lightning strokes that bypass the OHGW transfer all their surge energy through a single arrester into the phase conductor and this arrester placement is called on to dissipate significantly higher levels of charge and energy. The larger-diameter, heavier MOV elements were used on the top phases of the double circuit line to deal with the anticipated energy associated with shielding failures. A hollow strut assembly provided an interior volume for the stack of cylindrical MOV blocks with diameters of 61 and 76 mm. Perhaps the first recorded application of a metal-oxide type TLSA occurred in the early 1980s when a 138 kV line with single overhead ground wire was converted to a вЂcompactвЂ™ construction by restraining the lateral motion of phase conductors. A third vibration mode: wake induced oscillation affects only bundled conductors and is not discussed. The later involves complex vertical, longitudinal and torsional motions that accumulate thousands of stress cycles, almost invariably with an ice layer on conductors. Vibration modes considered are: Aeolian type low amplitude high frequency vertical vibration that accumulates millions of stress cycles and galloping, which is large amplitude low frequency oscillation. Havard reviewed cases of interaction of TLSAs with vibration dampers as well as other line hardware such as aircraft marker balls, anti-galloping de-tuning pendulums, clamps on spacer dampers and post insulator struts. This is of particular concern since current line design practice sees generally higher conductor tensions and therefore greater need for vibration control. Moreover, some TLSAs have been installed in ways that negatively impact or even completely defeat the protection provided by Aeolian vibration dampers.

Should a lead break away from a tower or the bottom of the arrester, its uncontrolled motion under wind can reduce electrical clearances.

Perhaps the most common of these is degradation of the components associated with flexible leads. However, they have also been known to experience a number of mechanical problems in service. Transmission line surge arresters (TLSAs) have become an important design and mitigation alternative to improve grounding and reduce investment in overhead ground wire.