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 Post subject: Switchgear "tracking-corona" precursor to failure
PostPosted: Thu Dec 31, 2009 10:22 am 
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Pictures of unattended switchgear, maintenance testing and inspections are important. This is what an arc flash looks like befopre it happens.


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PostPosted: Mon Jan 11, 2010 1:50 pm 
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Location: Lawrenceburg KY
What was the analysis of the failure?


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PostPosted: Mon Jan 11, 2010 2:21 pm 
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Johnh wrote:
Pictures of unattended switchgear, maintenance testing and inspections are important. This is what an arc flash looks like befopre it happens.


Easily detected with non intrusive PD surveys. We use a hand held detector and can survey a line up in a few minutes.

Here is a basic overview

http://www.nooutageelectricaltesting.com/PDF/level1.pdf


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PostPosted: Mon Jan 11, 2010 2:42 pm 
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Zog wrote:
Easily detected with non intrusive PD surveys. We use a hand held detector and can survey a line up in a few minutes.

Here is a basic overview

http://www.nooutageelectricaltesting.com/PDF/level1.pdf


Got a part number for that handheld?
Maybe I'll buy one :)


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PostPosted: Mon Jan 11, 2010 7:19 pm 
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Canuck01 wrote:
Got a part number for that handheld?
Maybe I'll buy one :)


I can set you up with one along with a training program how to use it. PM me for more info.

Basically the survey hand held detector is used to find PD issues, then a level 2 PD analysis is done to pinpoint the problem area. This system is common place in the UK in generation and industrial facilities and the technology is now gaining popularity here in the US.


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PostPosted: Sun Feb 28, 2010 3:21 am 
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were suppose to go with this

http://www.uesystems.com/why_up_apps_electrical_inspection.asp

but the link you gave seem more usable in day to day

and in the pdf i saw circuit breaker vibration analysis...never heard of this one

does someone would please give some comment


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PostPosted: Fri Mar 26, 2010 6:53 am 
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moreause wrote:
and in the pdf i saw circuit breaker vibration analysis...never heard of this one

does someone would please give some comment


It is also refered to as First trip. The main issue here is that an arc flash study relies on accuarte opening times, traditional breaker testing requires the breaker to be opened and removed from the switchgear, then tested via primary injection, the problem with this method is that if the breaker has not been operated in a long time the dried grease can delay the opening time, after the breaker has been cycled the times typically are shorter. When the breaker gets opened to be revomed for testing, the real opening time data is lost.

A special transducer is magnetically coupled to the front of the breaker. After the technician moves from the exposure zone, the breaker is operated. The transducer sends valuable vibration signals that represent breaker first trip timing and mechanical condition to a handheld analyzer. This unique breaker vibration signature is compared to a database library of known signatures.

Post test analysis can include superimposing the test breaker signature upon good breaker signatures, to quickly spot potential problems. Should the breaker fail the first trip test in the field, it is necessary to perform complete shop reconditioning or remanufacturing in order to return the breaker to a condition that will ensure proper operation and validate the arc-flash study. Frequent performance of the breaker vibration signature test ensures performance and exercises the breaker mechanism.


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PostPosted: Tue Oct 26, 2010 6:39 pm 
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Zog wrote:
Easily detected with non intrusive PD surveys. We use a hand held detector and can survey a line up in a few minutes.


Zog wrote:
Basically the survey hand held detector is used to find PD issues, then a level 2 PD analysis is done to pinpoint the problem area. This system is common place in the UK in generation and industrial facilities and the technology is now gaining popularity here in the US.


Are you actually seeing non-intrusive pd survey's being performed during routine inspections or on a scheduled basis? I've honestly never heard of that technology. It would certainly be nice to not wait until you walk into an aisle way of some switch gear to the aroma of ozone and the sizzling of tracking.

I've actually spent the last few days disassembling the cross-over bus of some old ABB switch gear and hi-potting to find the problem areas. Thankfully, it was caught early enough to jumper the line and shut the position and bus down to perform the work.


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PostPosted: Tue Oct 26, 2010 7:05 pm 
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Zog wrote:
It is also refered to as First trip. ...A special transducer is magnetically coupled to the front of the breaker. After the technician moves from the exposure zone, the breaker is operated. The transducer sends valuable vibration signals that represent breaker first trip timing and mechanical condition to a handheld analyzer. This unique breaker vibration signature is compared to a database library of known signatures.


Those could be some startling results. It's disturbing enough seeing the results of a breaker timing at the start of a routine inspection, after the first trip, compared to the results after a complete breaker inspection.


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PostPosted: Wed Oct 27, 2010 5:40 am 
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Legion wrote:
Are you actually seeing non-intrusive pd survey's being performed during routine inspections or on a scheduled basis? I've honestly never heard of that technology. It would certainly be nice to not wait until you walk into an aisle way of some switch gear to the aroma of ozone and the sizzling of tracking.

I've actually spent the last few days disassembling the cross-over bus of some old ABB switch gear and hi-potting to find the problem areas. Thankfully, it was caught early enough to jumper the line and shut the position and bus down to perform the work.


Yes, our field service crews carry them and many of our customers do the level I surveys themselves. PM me for more info if you want.


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