Capacitors

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Marion Catlin

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Jun 12, 2016, 1:30:10 PM6/12/16
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Hi just wondering if anyone know why capacitors burn out? It has happened to two of our bits of equipment recently in our railway arch workshop - that is an extractor fan a few weeks ago and now a pottery wheel, which admittedly has not been used for about 5 years but after starting up ran for about half an hour before blowing. Taking it apart revealed this (see photo) which we assume is a capacitor but don't really know 
Marion
ps arch electrics were tested recently

Pottery wheel motor.JPG
capacitor.jpg

Dan Herring

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Jun 12, 2016, 2:01:43 PM6/12/16
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Bring it along tomorrow it's hard to see from the photos.

Marion Catlin

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Jun 12, 2016, 2:10:55 PM6/12/16
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Yes, I will though we have a good company near us and I think Andrew will take it round there. Just wondering why two similar bits should blow
I don't even know what a capacitor does!

Marion Catlin BA(Hons) Design PGDip Cultural Planning AD:UK Senior Fellow
Free range cultural development and communications professional 
specialising in arts, culture and heritage

Director The Shift Norwich: Culture Shift, Design Shift and Digital Shift
Developing and promoting Norwich as a city of culture
Arts Development UK East Regional Co-ordinator
Project manager write2screen network
​ 
and Creative Futures
Steering group member Sistema in Norwich
Convenor: Music in Norwich and Art in Norwich Forums
​Founder member Norwich Hackspace and What Next? Norfolk​

Telephone office 01603 765353  Mobile 07946 261651
LinkedIn Marion de Mello Catlin  Skype marionecatlin
Twitter accounts marionofnorwich and norwichcultcity


On 12 June 2016 at 19:01, Dan Herring <djherr...@gmail.com> wrote:
Bring it along tomorrow it's hard to see from the photos.

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Karl Ablitt

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Jun 13, 2016, 4:02:37 AM6/13/16
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I believe that the capacitor on an AC motor provides a reservoir of energy to help deliver extra current on startup,  when there's a spike of current demand from the motor.  As I understand it inside the capacitor there is one, very large surface area conductor that is insulated from itself with a very thin insulating layer (the dielectric). Electrons flow into the conductor but can't escape due to the dielectric and so just end up hanging around in the cap until there is demand for them. The dielectric breaks down over time until it loses its insulating properties and a short developes in the cap, rendering it unable to store energy anymore! 

Toby Catlin

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Jun 13, 2016, 4:13:56 AM6/13/16
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Think of it like a water wheel. You need an initial flow of water to start the wheel spinning but once it is moving you need less water to keep it going. A capacitor is like a big bucket that can hold that water and discharge it very quickly when needed. They are used to smooth the flow of electricity (specifically current) when the load is changing, like a motor starting up or a LED turning on.

To work they need a liquid inside which can dry out and stops it from working. This can happen over time and is often the cause for old electronics to die or it can happen if too much voltage is put in.

To fix all you need to do is get a new capacitor of the same value (Farads) and resolder it back in.

txxx

Marion Catlin

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Jun 13, 2016, 4:31:15 AM6/13/16
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Thanks Karl
That is a good explanation, even I can understand it!
Marion

Marion Catlin BA(Hons) Design PGDip Cultural Planning AD:UK Senior Fellow
Free range cultural development and communications professional 
specialising in arts, culture and heritage

Director The Shift Norwich: Culture Shift, Design Shift and Digital Shift
Developing and promoting Norwich as a city of culture
Arts Development UK East Regional Co-ordinator
Project manager write2screen network
​ 
and Creative Futures
Steering group member Sistema in Norwich
Convenor: Music in Norwich and Art in Norwich Forums
​Founder member Norwich Hackspace and What Next? Norfolk​

Telephone office 01603 765353  Mobile 07946 261651
LinkedIn Marion de Mello Catlin  Skype marionecatlin
Twitter accounts marionofnorwich and norwichcultcity


On 13 June 2016 at 09:02, Karl Ablitt <karla...@gmail.com> wrote:

Marion Catlin

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Jun 13, 2016, 4:33:31 AM6/13/16
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Thanks. Andrew can get a new one from the place behind us on Europa Way and as this wheel hasn't been used for some time, drying up could easily have occurred so I suspect it is easily sorted but just was wondering what causes it
Thank you

Marion Catlin BA(Hons) Design PGDip Cultural Planning AD:UK Senior Fellow
Free range cultural development and communications professional 
specialising in arts, culture and heritage

Director The Shift Norwich: Culture Shift, Design Shift and Digital Shift
Developing and promoting Norwich as a city of culture
Arts Development UK East Regional Co-ordinator
Project manager write2screen network
​ 
and Creative Futures
Steering group member Sistema in Norwich
Convenor: Music in Norwich and Art in Norwich Forums
​Founder member Norwich Hackspace and What Next? Norfolk​

Telephone office 01603 765353  Mobile 07946 261651
LinkedIn Marion de Mello Catlin  Skype marionecatlin
Twitter accounts marionofnorwich and norwichcultcity


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