# Magnetic Starter Melt



## 20year man (Jul 9, 2013)

Working on a roof exhaust fan. Opened the hood and starter has melted! 208 3phase. I have seen burned coils b4 but the housing was melted like someone took a torch to it ....any ideas?


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## HARRY304E (Sep 15, 2010)

20year man said:


> Working on a roof exhaust fan. Opened the hood and starter has melted! 208 3phase. I have seen burned coils b4 but the housing was melted like someone took a torch to it ....any ideas?


Someone must have took a torch to it....:jester::laughing:


How about water getting in, that will cause corrosion then arcing and that will cause melting if the over current device is not working.


Welcome to ET....:thumbup:







.


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## union347sparky (Feb 29, 2012)

Starter sized correctly?


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## 20year man (Jul 9, 2013)

No water totally covered by roof hood as a matter of fact there were 5 just like it!


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## Wirenuting (Sep 12, 2010)

Oversized o/L's + new motor + wrong belts + belts to tight + loose connections + worn contact points = melted starters. 

Add 2 points if its an older starter were only 2 phases have o/l protect as it equals occasional single phasing. 

Seen it often enough.


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## JRaef (Mar 23, 2009)

Most likely, chattering of the contactor due to a bad control circuit, either a loose connection, failing power source or defective control element, i.e. BMS output or whatever is supposed to be telling that exhaust fan to turn on. Meltdown can happen in a matter of minutes if the chattering is severe. The heat that gets trapped inside the contacts of the contactor has little direct relationship to the amount of current flow, so protective elements like overload relays cannot act fast enough to protect the contactor itself. 

I'd be willing to be its a DP contactor too... They start off life as marginal at best.


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## John Valdes (May 17, 2007)

Loose connection got hot and burned slowly until you found it.


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## IslandWire (Aug 3, 2013)

I had a fused knife switch looked like someone took a torch to the inside of it once. It was a loose screw that held the fuse clip to the wire terminal. Look for the source of heat(the worst damage) and see if anything looks like it was not tight enough.


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## 20year man (Jul 9, 2013)

Yeah i guess it could have been a connection in the control side. I took pics but the app keeps crashing...


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## 20year man (Jul 9, 2013)

Oh i guess the picture app works!!!


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## IslandWire (Aug 3, 2013)

Well, looking at the smoke stain on the front center, I would think that one or more of the contacts resistance got raised. There could have been contact damage, ants/bugs, or general debris between the contacts and they did not fully close. I have seen pieces of plastic and metal filings fall inside of contactors and cause some strange problems.

If you are bored, I would take the thing apart right down to the contacts and see what really happened. Maybe before you take it apart, jam the contactor closed manually and read the resistance on all 3 poles.


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## just the cowboy (Sep 4, 2013)

The aux contact looks smoked also. This may be the cause of chatter JReaf spoke of. I assume that the control voltage is 208v also? Replace all that cloth wire to start with.


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## JRaef (Mar 23, 2009)

just the cowboy said:


> Replace all that cloth wire to start with.


Yeah, no kidding!


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