> Seriously Olin, keep ... Ignore the rude bits. He can't help it. Not worth the hassle. Concentrate on the useful technical gems hidden amongst the dross. > your shorts. So I didn't feel like saying a connector with 12 volts > across > it and 6 amps through it. It's easier to say 12 volts and 6 amps > through > it. You understand what I'm asking. He may not. I take it that you mean that you have two systems which draws 6 amps from either a 12v or 60v supply respectively. The actual drop across the connector junctions in such cases will (hopefully!) not be the system voltage. The connector may "see" the system voltage between a current carrying connector and an adjacent one but only leakage current will flow across this path. The actual connector voltage drop would usually be well under a volt and hopefully only millivolts. If you assume that leakage current between adjacent contacts or from contacts to ground is minimal then heating comes essentially only from the product of current and contact voltage drop or current squared x contact resistance - as Olin says. The latter is the best way to look at it - power = I^2R. Clearly the system voltage is not involved directly. There is an important special case in which Olin's answer is quite wrong technically. It's unlikely to apply in the specific example voltages that you gave, but, as you were only giving examples, and you wanted a general answer, then it's a good illustration of how one needs to keep an open mind and try and understand the general intent of a question rather than getting all flustered with the terminology and partially missing the point. Special case: Contact resistance is *never* constant with current or even linearly variable with current (for most values of never :-) ) but in the overwhelming majority of the time it's close enough to constant for practical purposes to allow a maximum value to be used. Most times you don't care if it's lower than spec. However at very low voltages *across the contacts* (which is what Olin missed) and/or low currents through the contacts the contact resistance can be much or much much much higher than usual. The actual voltages and currents involved are usually small by practical standards and vary with contact materials. Some materials which have excellent low contact resistances "once they get going" are notoriously bad below some critical threshold. This phenomena is addressed by the notion of 'wetting current" (Google knows). At 10A through or 12V available system voltage you would be most unlikely to find normal materials that has a wettting current problem, but it could perhaps happen. In such cases the power loss in the connector is liable to be higher with reduced system voltage. But, the rest of the time, it's likely that current though the contact points is well correlated with power loss in the connector, regardless of system voltage. Russell McMahon But instead of being polite, as most > people are to you, you constantly feel the need to respond like > you're an > A**. > > So do me a favor. If you can't respond to my questions politely, do > not > respond at all. I really won't be the worst for it. > > > On 1/17/06, Olin Lathrop wrote: >> >> Shawn Wilton wrote: >> > Is it possible for a connector to produce more heat as a result >> > of >> > power dissipation at a voltage lower than it's rating? >> > >> > So say you have a power connector good for 10 A, and 60V. >> > >> > Will I get more heat off the connector if I run say 10A and 12V >> > through it? >> >> This question is a great example of why using terms properly can be >> important. Current goes thru things, voltage can be accross >> them. Voltage >> thru something is just gibberish. >> >> A connector is intended to have as low a resistance as possible. >> It will >> be >> designed to carry some maximum current. The voltage accross the >> connector >> at any time is the current thru it times its resistance. Ohms law >> states >> that V = I * R. If R is fixed as it is with a connector, you only >> get to >> pick one of V or I. >> >> The voltage spec of a connector refers to the open voltage or the >> insulation >> voltage between adjacent pins or to some other point. >> >> > I could see a small possibility if you model the connector with >> > reactive components, but to me, the obvious answer is no. >> >> I don't see how you can answer a question that doesn't make sense >> in the >> first place. >> >> > If you say yes, please give a good explanation. >> >> A good explanation requires a good question. >> >> >> ****************************************************************** >> Embed Inc, Littleton Massachusetts, (978) 742-9014. #1 PIC >> consultant in 2004 program year. http://www.embedinc.com/products >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > > > -- > > > Shawn Wilton (b9 Systems) > http://black9.com > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist