Resistance heating of electrical connectors?
Resistance heating of electrical connectors?
(OP)
Does anyone know where to find some good information and data on the phenomena of resistance heating of electrical connections. I have an appliance product that is getting repeated overheating failures at its two pin power connection. The connection is often disconnected and reconnected. The device only draw 2 amps but we are still seing signinifacnt heating after several cycles of use of the connector. Also any leads on manufacturers that supply haevy use connectors would be appreciated. I am hoping to find connectors that would be similar in size to those used to connected notebook computer power supplies. Thanks,
Phil
Phil





RE: Resistance heating of electrical connectors?
It often relates to the scrubbing of the surface material caused by plugging and unplugging.
Sometimes you change materials, coatings, or thicknesses to fix the problem.
A picture would certainly be useful in helping the discussion as I can think of hundreds of different "connectors".
Also since every connection incurs a resistance which will heat up based on:
Power = Current(squared) x Resistance
there will always be some heating at a connector. Remember too that all chemical reactions double their rates for every 10 degree rise in temperature. This means some part that is 20 degrees hotter then the rest of the stuff will oxidize and fail 4 times faster then the cooler stuff nearby.
The solution is often providing the design with heat sinking for the connectors. For example connectors that might work great in the air may overheat if buried in some plastic molded housing. One solution would be to attach wires substantially larger to one or both sides of the connector to assist in conducting the connection power away to areas that have more heat rejection ability.
RE: Resistance heating of electrical connectors?
Phil
RE: Resistance heating of electrical connectors?
http://www.connectpositronic.com/Power/
RE: Resistance heating of electrical connectors?
See the FAQ:
FAQ238-1161
or link to a vendor picture. Your app if strange/unique would benefit, probably from an actual picture.
RE: Resistance heating of electrical connectors?
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Resistance heating of electrical connectors?
http://tinypic.com/ke98nq.jpg
http://tinypic.com/ke99hz.jpg
http://tinypic.com/ke9bex.jpg
http://tinypic.com/ke9c7a.jpg
RE: Resistance heating of electrical connectors?
I would study the problem.. Gut the tool so you have just the connectors mounted normally. Then using a scope monitor the current across a small resistor as you wiggly the connector. You may find that it makes really bad contact in certain cases. This would indicate the spring aspect of your connector is weak/bad or highly directional.
You can also do a plug/unplug test. Do a graph showing the contact resistance as a function of insertion number. Use an ohmmeter that goes sub-ohms. You may find that the gold scuffs off in a few dozen insertions. (jraefs example)
Rarely is gold ever used in charger connectors as it is so soft it always wears away quickly. Hence a connector may have a very low contact resistance initially but quickly loses this with wear, whereas a silver contact may have a higher initial contact resistance but it never increases appreciably with use. Keep in mind that if the user is plugging in a power supply that is on it may arc the gold off very quickly.
RE: Resistance heating of electrical connectors?
RE: Resistance heating of electrical connectors?
I read this that it keeps happening. Silly question, but, you are replcing the plug (male) as well as the recepticle (female) aren't you? And they are physically the correct size for each other, right?
Scott
In a hundred years, it isn't going to matter anyway.
RE: Resistance heating of electrical connectors?
We will probably replace the pin and sockets as a set. Right now we are trying to understand the exact cause of failure and select a new pin/socket product for future units so that know we won't get this problem again, thanks again,
Phil
RE: Resistance heating of electrical connectors?
A problem with non-concentric connectors is auto alignment.. It is easy to have this happen with parallel conductors especially if the pins get banged.
I look at Mouser and Digikey and they have quite a few co-axial power connectors rated up to 3 amps.
Straight copper can have some issues too. That's why power connectors are generally plated (see the ones mentioned above) or... they are solid brass.
RE: Resistance heating of electrical connectors?
Your last two picture are not congruent. You show a male plug corroded, burnt and melted from heat but the mating female component is bright and clean and no heat stress. Whats Up?
or did I miss a pic...
pennpoint
Best regards
pennpoint
RE: Resistance heating of electrical connectors?
He has a pic of each sex that is fried.
RE: Resistance heating of electrical connectors?
Also, do you do the rubber/plastic over- molding of the connectors and at what temperature?
RE: Resistance heating of electrical connectors?
Phil