Drive Died (arcing between pins on the PCBA)

  • Thread starter Thread starter MaintenanceMGR
  • Start date Start date
  • Tags Tags
    Drive
AI Thread Summary
A drive in a production area has failed multiple times due to arcing between two closely spaced inputs on a control board, raising concerns about potential contamination or gases causing the issue. The environment is clean and dry, and the drive operates at a low voltage of 480V, which typically does not support arcing at such short distances. Suggestions include examining the area for contamination, considering cleaning and conformal coating, and investigating if any environmental changes occurred before the failures. The possibility of manufacturing defects, such as tin whiskers from lead-free solder, is also noted as a potential cause. Overall, further investigation into the specific conditions and components involved is necessary to determine the root cause of the arcing.
MaintenanceMGR
Messages
3
Reaction score
0
Hello:

I have a problem with a drive located in a small production area. It has failed three times due to arcing between two inputs to a control board. These inputs are about 5mm apart and the manufacturer is saying that this could be from material collecting on these terminals or from gases. Now I can understand material conducting between the inputs, but gases seems rather far fetched. The drive is not sealed and it is at regular atmospheric pressure and cooled with a small muffin fan. The drive does not use any high voltage conversion and the input voltage is only 480V. I remember that it usually takes about 3000V/mm for a spark to develop in air, but I can't find any thing in that range in the drive.

My question is it possible for an arc to develop spontaneously between to points 5mm apart? And if it is what are some examples of voltage or gases that may be present to facilitate such an event.

BTW: Please forgive my ignorance on some of this, I know enough only to get things wrong.
 
Engineering news on Phys.org
MaintenanceMGR said:
Hello:

I have a problem with a drive located in a small production area. It has failed three times due to arcing between two inputs to a control board. These inputs are about 5mm apart and the manufacturer is saying that this could be from material collecting on these terminals or from gases. Now I can understand material conducting between the inputs, but gases seems rather far fetched. The drive is not sealed and it is at regular atmospheric pressure and cooled with a small muffin fan. The drive does not use any high voltage conversion and the input voltage is only 480V. I remember that it usually takes about 3000V/mm for a spark to develop in air, but I can't find any thing in that range in the drive.

My question is it possible for an arc to develop spontaneously between to points 5mm apart? And if it is what are some examples of voltage or gases that may be present to facilitate such an event.

BTW: Please forgive my ignorance on some of this, I know enough only to get things wrong.

Welcome to the PF.

If the atmosphere is wet and dusty, there could be an accumulation of gunk that helps the arc to happen. Do you see evidence of contamination in other areas of that PCB assembly? Have you considered cleaning and conformally coating the PCBA in that area?
 
berkeman said:
Welcome to the PF.

If the atmosphere is wet and dusty, there could be an accumulation of gunk that helps the arc to happen. Do you see evidence of contamination in other areas of that PCB assembly? Have you considered cleaning and conformally coating the PCBA in that area?

The area is pretty clean and not wet. Specifically the area is a show area for customers that does small production runs, so they keep up with standards very well. Also the drive has been installed for 6 months, and recently the original failed and then two replacements failed as well, within 2 weeks from start to finish. So contamination could have caused the first but the succeeding two, ??
 
MaintenanceMGR said:
The area is pretty clean and not wet. Specifically the area is a show area for customers that does small production runs, so they keep up with standards very well. Also the drive has been installed for 6 months, and recently the original failed and then two replacements failed as well, within 2 weeks from start to finish. So contamination could have caused the first but the succeeding two, ??

Also we have conducted a study on the incoming power feed, which had nothing of note within a ten day study. My gut is telling me this could be manufacturing issue, but I don't want to take a stand on this without a better understanding of the science and how arc's can form.
 
How can you be sure that it was arcing between those 2 pins that caused the failures? Was anything else changed in the environment around the drive shortly before the first one failed? Like a new piece of equipment being used/installed nearby?

Can you post a picture of the pins you are talking about?
 
Lead free solder is notorious for "whiskers". Search on "tin whiskers"

http://nepp.nasa.gov/whisker/Is the arc-over right at a soldered joint?
If so,
Try applying a dab of "Glyptol" insulating paint, or ordinary polyurethane woodworker's varnish (oil based) over the solder pads on the next board.

I'd guess 480 makes quite a flash when it goes. Current limiting fuses like Shawmut 101 might help preserve some clues.
 

Thread '2:1 Pulley Question'

I have Mass A being pulled vertically. I have Mass B on an incline that is pulling Mass A. There is a 2:1 pulley between them. The math I'm using is: FA = MA / 2 = ? t-force MB * SIN(of the incline degree) = ? If MB is greater then FA, it pulls FA up as MB moves down the incline. BUT... If I reverse the 2:1 pulley. Then the math changes to... FA = MA * 2 = ? t-force MB * SIN(of the incline degree) = ? If FA is greater then MB, it pulls MB up the incline as FA moves down. It's confusing...
View full post »

Thread 'Why do all my clocks run slow?'

Hi. I noticed that all electronic devices in my household that also tell time eventually lag behind, except the ones that get synchronized by radio signal or internet. Most of them are battery-powered, except my alarm clock (which runs slow as well). Why does none of them run too fast? Deliberate design (why)? Wrong temperature for quartz crystal? Decreasing battery voltage? Or just a coincidence?
View full post »

Similar threads

Cause of multiple paths of electrical breakdown?
Replies
5
Views
2K
Oxygen Enriched Internal Steam Compression Ignition Engine (OEISCIE)
Replies
14
Views
5K
Can we measure the effective mass of charge carriers using a centrifuge?
Replies
24
Views
5K
B Infrared Detectors & The 2nd Law of Thermodynamics
4
Replies
152
Views
10K

Hot Threads

Recent Insights

Back
Top