Vidéos & Photos
 
Index des vidéos

Video 1 : essai d'investigation sur matériel en ligne : Cliquez ici pour voir la vidéo
Explication ? (voir plus bas), other videos on arcing faults on http://205.243.100.155/frames/longarc.htm#Longspark
Credit: Bert Hickman, Stoneridge Engineering, http://www.teslamania.com

Video 2 : le galop des lignes à haute tension : Cliquez ICI pour voir la vidéo
Plus ? Cliquez ICI ou alors ici

Video 3 : les effets mécaniques des courants de court-circuit dans un poste à haute tension : Cliquez ICI pour voir la vidéo
Plus ? Cliquez ICI
Video 4 : les réseaux du futur évoluent vers les "smart grid" , visualiser la video accessible à :  http://www.smartgrids.eu/
Video 5 : Interview J.L. Lilien sur le projet Ampacimon (mesure en temps réel de la puissance que l'on peut soutirer d'une ligne électrique) et le projet Makola (alimentation électrique en zone rurale dans un pays en voie de développement). Ces projets sont présentés dans le cadre Planet-ULg. Vidéo prise et montée par Daniel Bay.
video 6 : travaux à haute tension (ligne aérienne)  ou    ici ou encore ici


Index des photos
Réalisation_makola_Congo_Brazzaville_2002.jpg
idem_autre_vue
réalisation d'une installation de 50 kVA par soutirage inductif sur une ligne 220 kV située en brousse. Primaire entre phase et terre locale.


A lightning stroke hits an earth wire (courtesy Niagara Mohawk Power corporation).
Phew.. It's working. (http://www.nationalgridus.com/niagaramohawk/)




(extrait de http://205.243.100.155/frames/longarc.htm#Longspark) (Courtesy : Bert Hickman)
This video clip was captured at the 500 kV Eldorado substation near Boulder City, Nevada by power company engineers and maintenance staff.

It shows a three-phase air disconnect switcher attempting to open the high voltage supply to a large three phase shunt line reactor. The line reactor is the huge transformer-like object behind the truck at the far right at the end of the clip. Line reactors are large iron core coils which are used to compensate for the effects of line capacitance on long extra high voltage (EHV) transmission lines. Internally, each phase of the reactor is connected through a large coil to ground. Each coil within the reactor is capable of providing 33.3 Million Volt Amperes of inductive reactance (MVAR) at 290 kV between each phase to ground.

The power company was having difficulty cleanly disconnecting one phase of the line reactor and had set up a special test to videotape a switching event so that they could better diagnose the problem.
The engineers had also made arrangements to kill the experiment by manually tripping an upstream Oil Circuit Breaker (OCB).
This particular switcher uses gas filled switching elements, called gas puffer interrupters. These are located just to the right of the rotary air break switches. The interrupter uses switching elements that are housed in sealed bottles filled with a special insulating gas (sulfur hexafluoride, SF6) under pressure. SF6 helps to rapidly extinguish the arc that's created whenever a high voltage circuit is broken.
During normal operation, the switcher would first open the SF6 interrupters. This would disconnect the HV circuit so that the air break switches could open with no current flowing. Once the air break switches had completely rotated to the open position, the SF6 interrupters would then reclose. The actual SF6 interrupter switching elements are hidden inside the gray horizontal insulators (bushings). These particular interrupters use two SF6 bottles that are electrically connected in series. It takes two switches in series to share the high voltage stress - a single switch can't handle the voltage.

In this video, one of the pairs of SF6 interrupters fails to open. This places the entire voltage stress across the remaining good interrupter. As the good one valiantly tries to open the inductive load, it creates a high voltage surge that causes the bushing of the good interrupter to flash over.
The initial flashover can easily be seen at the very beginning of the video clip.
Since the affected phase remains energized (through the conductive arc), the air break switch begins to open hot. It continues arcing as the switch rotates 90 degrees to the fully open position. Once the air break switch reaches the fully open position, the SF6 interrupters then reclose. Although this extinguishes the horizontal arc across the good interrupter's bushing, the arc across the air break switch persists, continuing to grow and creating a very dangerous situation.
The arc stretches upward, driven by rising hot gases and writhing from small air currents, until it easily exceeds 100 feet in length. Switching arcs usually self-terminate long before reaching this size since they normally flash over to an adjacent phase or to ground. Once this happens, it becomes a detectable fault, tripping out (disconnecting) the circuits.
A phase-to-phase arc can be seen at the very end of the previous 345 kV air break switch video, just before the resulting short circuit trips an upstream OCB. Since the 500 kV arc was in open air and was sufficiently removed from adjacent phases, it could have persisted for quite some time.

To avoid risking further damage to their equipment, the utility manually commanded an upstream OCB to open, abruptly extinguishing the arc.
After this event, it was determined that both SF6 switch bottles in the affected phase had sustained permanent damage. The bottles were then sent back to the manufacturer for analysis to determine the root cause of the problem. Loss of insulating SF6 gas inside an interrupter bottle is suspected as the initial cause of the switching failure.

As impressive as this huge arc may be, the air break switch was NOT disconnecting a real load. This arc was only carrying the relatively low (perhaps 100 amps!) magnetizing current associated with the line reactor.
The 94 mile transmission line associated with the above circuit normally carries over 1,000 megawatts (MW) of power between Boulder City, Nevada (from the generators at Hoover Dam) to Los Angeles, California. A break under normal load conditions (~2,000 amps) would have created a MUCH hotter and extremely destructive arc. Imagine a fat, blindingly blue-white, 100 foot long welding arc that vaporizes the contacts on the air break switch and then works its way back along the feeders, vaporizing them along the way.

Still, you've gotta' admit that this little 33 MVAR arc is certainly an awesome sight! And, who says utility guys don't have any fun - just listen to lineman on the right whoop at the end of the clip!



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