Bad contactor?

[Sublime8365]

I built a 120V e-HERMS system about 2.5 years ago and during my last batch, the contactor started sparking (not a lot, but obviously any sparks are bad news). I was able to complete my brew without the control panel so I haven't used the contactor since. The pole that was sparking is slightly blackened and the terminal spade was partially burnt as well.

So my question is - could this have anything to do with the wiring in my control panel - which hasn't changed at all in the 2.5 yrs of successful brews with this system, or should I chalk this up to a contactor that just failed over time?

 

[EZCyclone]

Electrical connections loosen over time. Go through and tighten every connection in your system. clean that terminal and make sure the spade connector is clean and tight, if it's lose, replace it. You can clean the contacts with 600 grit wet dry sand paper. Make sure you keep it perfectly flat so as not to wear away on the contact angle. If you have a ammeter put it on that wire for the next brew day and watch your current draw.

 

[Facinerous]

I agree with EZCyclone in all things, but he forgot to mention why. Checking all your connections is a good thing, and cleaning the contact on your contactor may fix it.

What I would reason to guess is the current that is drawn through the points on your contactor is close to the max rating of it. So over time the terminals which do the switching will wear down due to arcing of breaking the current. Over time those contact points will wear down to a point where you get what you observed.

If you were to find a new relay which has a greater amp rating then that should increase the service life of that relay tremendously.

 

[EZCyclone]

I agree with EZCyclone in all things, but he forgot to mention why. Checking all your connections is a good thing, and cleaning the contact on your contactor may fix it.

What I would reason to guess is the current that is drawn through the points on your contactor is close to the max rating of it. So over time the terminals which do the switching will wear down due to arcing of breaking the current. Over time those contact points will wear down to a point where you get what you observed.

If you were to find a new relay which has a greater amp rating then that should increase the service life of that relay tremendously.

Totally agree here. Now that said, if your contact points are beefy enough often you can reshape them back to making flat contact with each other. Although if you have to do this, its a stop gap to get you going until you get a new contactor. The price doesn't jump very much per amp increase. So go as big as you can. I tend to try and run contactors and relays at a double rating. But try not to go below about 30% more Amps than your system is calling for.

 

[augiedoggy]

Totally agree here. Now that said, if your contact points are beefy enough often you can reshape them back to making flat contact with each other. Although if you have to do this, its a stop gap to get you going until you get a new contactor. The price doesn't jump very much per amp increase. So go as big as you can. I tend to try and run contactors and relays at a double rating. But try not to go below about 30% more Amps than your system is calling for.

I used to file the contacts as a temporary fix after ordering a replacement in the equipment I service... they usually have some sort of non corrosive coating that once damaged will cause them to keep corroding burning quickly with current after "cleaning them up" I agree though that only certian relays or contactors would fail in the equipment I saw and they were usually from

A, a lot of switching on and off

B, a large amp load placed on the contacts closer to the max rating.

that said I use 25A relays in my setup and no issues so far in over a years worth of use (knock on wood)

 

[EZCyclone]

I use two 5HP relays in my hot tub alone with a 25A relay for the heater which draws 20A and ha e no issues. If the eheater relay goes it will be replaced by a 40A.

 

[processhead]

Although you did not specifically mention any spade connectors as the location of a loose connection, I have found they are more susceptible to overheating and loosening over time when run at higher current levels.

Many relay contacts are plated at the factory. Filing plated contacts that are pitted is a short term fix at best.

 

[EZCyclone]

clean that terminal and make sure the spade connector is clean and tight, if it's lose, replace it.

I did, right there ^. As far as the plating being warn off when abrasively cleaning the contacts on the contactor it'self, if it's arcing like he says, that factory plating is long gone. Blown away as the white hot glowing sparks themselves. So no harm here in cleaning up the surface to create a better contactor geometry. A flatter connection will carry more current, plated or not.