pdxmonkeyboy Posted February 7, 2018 Share Posted February 7, 2018 I have a question about contactor failure. thought i would throw it out there Sent from my SM-G930V using Tapatalk Quote Link to comment Share on other sites More sharing options...
cjmdh Posted February 7, 2018 Share Posted February 7, 2018 What kind of contactor? What's it for? AC DC? What's the control voltage? Quote Link to comment Share on other sites More sharing options...
Higher Thinking Posted February 7, 2018 Share Posted February 7, 2018 I know Vance is just about finished with his journeyman process. I think his screen name is@Vance164. Sent from my SM-G955U using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
albertareef Posted February 7, 2018 Share Posted February 7, 2018 2 hours ago, pdxmonkeyboy said: I have a question about contactor failure. thought i would throw it out there Sent from my SM-G930V using Tapatalk Ok... what did you do now? 1 1 Quote Link to comment Share on other sites More sharing options...
pdxmonkeyboy Posted February 7, 2018 Author Share Posted February 7, 2018 well, this happened yesterday... 40 amp two pole, normally open relay. Pushing about 28 amps though it. 8 gauge wire in, 10 gauge wire going out (to two seperate circuits.. each 14 amps).this is about the third time this has happened in about two years. I am trying to figure out WHY this is happening. i asked the guys at platt and they said.. your going to love this "it got to hot". Really?? all the relays flip.on and off twice a day. the contacts of the relay look fairly scored and pitted. Do you think that the daily arcing is wearing out the contacts so they are not making a good connection and thus shorting and over heating?? I am just thinking perhaps i should routinely replace them? Its odd though, they should have a much higher duty cycle. I have some 200 amp relays that are going on 4 years without a hiccup.thought? Sent from my SM-G930V using Tapatalk Quote Link to comment Share on other sites More sharing options...
albertareef Posted February 7, 2018 Share Posted February 7, 2018 That does not seem normal. Curious what @Vance164 might have to say. Quote Link to comment Share on other sites More sharing options...
cjmdh Posted February 7, 2018 Share Posted February 7, 2018 (edited) Yes, the contacts arcing over time will cause them to get pitted and also cause carbon build up. This increases the resistance across the contacts causing them to get hot. At some point the damage is too much and they either weld shut or just make enough contact to burn them up. A larger capacity contact or a 4 pole contact with two poles tied together to effectively make a two pole should solve the issue. You can also go solid state as long as you get the appropriate heatsink to go along with it. Edited February 7, 2018 by cjmdh Quote Link to comment Share on other sites More sharing options...
pdxmonkeyboy Posted February 7, 2018 Author Share Posted February 7, 2018 Yes, the contacts arcing over time will cause them to get pitted and also cause carbon build up. This increases the resistance across the contacts causing them to get hot. At some point the damage is too much and they either weld shut or just make enough contact to burn them up. A larger capacity contact or a 4 pole contact with two poles tied together to effectively make a two pole should solve the issue. You can also go solid state as long as you get the appropriate heatsink to go along with it.thanks man. thats what i figured was happening. I have zero experience with solid state relays. i thought they were only for low voltage stuff?? Sent from my SM-G930V using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
cjmdh Posted February 7, 2018 Share Posted February 7, 2018 Nope, use them quite a bit at work for 208v applications. Just need a good heatsink for the higher current stuff. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.