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Sherlock Ohms

Malfunctioning Fridge Causes Meltdown

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tekochip
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Platinum
Re: How can a microswitch collapse?
tekochip   10/1/2014 7:25:37 AM
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Maybe the real big ones have smoke detectors, but mine only has my nose.  The switch housing melted and bubbled but did not sustain a flame.

shehan
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Gold
Re: How can a microswitch collapse?
shehan   9/30/2014 10:07:16 PM
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@Soldering Gunslinger- Thanks for explaining that, I have heard that its used differently in each of these regions. 

shehan
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Re: How can a microswitch collapse?
shehan   9/30/2014 10:05:18 PM
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@Awile – yes this seems to be a one in a million failure if not the manufacturer would have already heard many complaints. 

shehan
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Gold
Re: How can a microswitch collapse?
shehan   9/30/2014 10:03:47 PM
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@tekochip – Yes if the connections were little resistive it would cause a fire. Aircrafts have smoke detectors and sensors to warn the pilots. 

shehan
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Gold
Re: How can a microswitch collapse?
shehan   9/30/2014 10:01:24 PM
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@naperlou – The latest smart refrigerators have a set of sensors and a control unit to identify a fault. I guess this refrigerator was not that smart. 

shehan
User Rank
Gold
Re: How can a microswitch collapse?
shehan   9/30/2014 10:00:03 PM
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@AnandY – I am pretty sure that it wasn't the slamming door, I guess there should be more reasons for this fire. 

William K.
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Platinum
Re: How can a microswitch collapse?
William K.   9/30/2014 8:22:30 PM
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I have used and abused quite a few microswitches over the years, and replaced a few broken ones as well. One thing is that the internals don't "collapse." When the switch fails due to a breaking leaf element it may close or not close, and it may possibly arc inside. One thing to remember is that in most of the UK the standard line voltage is 220 volts, rather than the 120 we are accustomed to here in the USA. The higher voltage may make arcing a bit worse, but actual Microswitch brand switches seem to be made of a material that would char and stink but not burn. Replacements of a much cheaper kind may be made of materials that are not so very fire resistant.

Given the standard materials that most refrigerators are made from it is also hard to imagine there being enough mass to burn that would produce enough smoke to do any damage.

Soldering Gunslinger
User Rank
Iron
Re: How can a microswitch collapse?
Soldering Gunslinger   9/30/2014 11:37:46 AM
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Oscar Wilde is quoted as saying that Brittain and the United States are two countries separated by a common language.

When we Yanks refer to a "Nurse", it generally means a medical practisioner.  On the other side of the pond, it can mean somebody who takes care of young children, so yes a Nurse might be in a home, specially one where expensive artwork may hang on the walls.

 

I remain,

 

The Old Soldering Gunslinger

a.saji
User Rank
Silver
Re: How can a microswitch collapse?
a.saji   9/30/2014 11:10:57 AM
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@Awile: Yes if you consider closely, the questions are reasonable. You should have some sort of a lead point towards it. 

Awile
User Rank
Iron
Re: How can a microswitch collapse?
Awile   9/30/2014 9:53:21 AM
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That failure seems like a one-in-a-million failure mode.  If the design team had considered mitigating for it, I suspect they would have beefed up the switch and terminals, rather than installing sensors.  

If the current didn't trip a breaker, what would be sensed?  What would be the response?  Would the risk of a false shutdown of the refrigerator create higher overall loss than suppression of smoking wires?

These kinds of questions keep us engineers scratching our  heads.

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