# Plant Switch Openings



## MDShunk (Jan 7, 2007)

That's normal when a big air switch open under load. Here's another one of a 345kv switch.

http://video.google.com/videoplay?docid=-3005249485929960832


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## MDShunk (Jan 7, 2007)

More information by the minute.


> 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 being supplied from a 94 mile long section of transmission line 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 can provide 33.3 Million Volt Amperes of compensating inductive reactance (MVAR) at 290 kV between each phase to ground . The power company had previously encountered difficulty interrupting one of the three phases when trying to disconnect the line reactor. Their power engineers set up a special test so that they could videotape a switching event, and they made arrangements to "kill" the experiment, if necessary, by manually tripping upstream circuit breakers.
> 
> 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 actual switching elements of these interrupters are hidden inside the gray horizontal insulators (bushings). The switching elements are housed within sealed "bottles" filled with a special insulating gas (sulfur hexafluoride, SF6) under high pressure. SF6 helps to rapidly extinguish the arc that's created when the high voltage circuit is broken. During normal operation, the switcher will first open the SF6 interrupters which disconnects the HV circuit so that the air break switches can open with no current flowing. Once the air break switches completely rotate to the "open" position, the SF6 interrupters then reclose. Normally, this sequence insures that the air break switches operate de-energized and arc free.
> 
> ...


Thanks to Sylvia Gallus for also refering this information.


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## MDShunk (Jan 7, 2007)

This is part of the fun of this site. We also get an update from Neil Brady, who was on the scene. 


> You're right about the Lugo Switcher on our 500KV line having problems. This was our first time trying to record the problem though. The 500KV line was isolated from the system and we fed from our 500KV bus in order to have control of de-energization by circuit breakers, without any interruption of power to the 500KV grid and jeopardizing the system. I was the maintenance foreman at Eldorado Substation, Boulder City, NV. when this ocurred and this is my video that I shot. The maintenance crew was at the truck (no linemen) and one of them is yelling at the end because the arc was so spectactular.
> 
> P.S. We HAD to open the 500KV CB to de-energize the arc. It would not extinguish by itself.


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## MDShunk (Jan 7, 2007)

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