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Aren Siekmeier 02-10-2014 13:38

Re: Electrical basics
 
Notice that between the different sizes, the actual contact area between two crimps is roughly the same. What's different is the size of wire they crimp onto, so the current rating is for the wire size, and isn't related to how much current the crimp itself can conduct.

So if a 30A crimp gets a good crimp on 10 or 12 gauge wire, it will certainly carry the current, since it has the same connection contact with another crimp as the 45A crimps do.

timytamy 02-10-2014 20:39

Re: Electrical basics
 
I kinda answered this question already:
Quote:

Originally Posted by timytamy (Post 1402553)
The amperage ratings on the contacts are slightly misleading. All the contacts are rated to 45A, however it's recommended you only pass the listed currents through as that is what APP considers safe for those gauges. eg you can put 45A through the 15A contact, however it's unlikely that the cable it's attached to will survive. That being said, always use an appropriate gauge for each circuit, and sized such that it is legal for the rules. However, if you have 18AWG wire on a 20A circuit (legal per 2014 rules) don't worry too much about using the 15A contact, it's more important you match the contact to the wire gauge than the contact to the current.

Perhaps I wasn't clear enough, the current ratings associated with each contact is only UL's conservative recommendation based on the WIRE they attach to. ie UL's thinks it's not the best idea to pass 40A through the 15A contact, because the 18AWG wire that it's crimped onto won't safely carry that current.

And here's the information straight from PowerWerx:
Quote:

The size of the wire a Powerpole contact will accept is the primary limitation of their ability to carry a load. The size of the flat contact area is actually the same for all 15, 30 & 45 amp contacts. Powerpoles will safely handle higher loads or surges, please read the PP30 data sheet (PDF) for additional information.
The current rating for a cable is actually a far more complex relationship than matching a certain current to a certain gauge, it varies depending on length of run, ambient temperature, melting temp of insulation, airflow around cable, conductor material, type of current, etc. It's actually perfectly safe to pass ~100A through something as small as say 20 AWG, if it's a very short run, this is actually how fuses work (but don't try this on your robot).

That being said generally, these properties are simplified into rating tables, for FRC, it's ok to pass 40A through a 12AWG cable since the longest run that you might have is one or two meters, however the usual application for APP may involve runs up through ten meters in more hostile environments, hence the more conservative ratings.

TLDR: Current ratings on the PPs don't mater, chose a wire that is appropriate for whatever current you are using, and then select the PP for that gauge.

Al Skierkiewicz 03-10-2014 07:32

Re: Electrical basics
 
Tim,
The UL ratings are actually based on heat rise for specific currents under continuous duty. So if the contact rises above a certain temperature after having that current flowing for 24 hours or more, then it will receive a lower rating. We use the 30's because we have lot's of them. We purchased 45 last year to give them a try but don't really feel they are needed in our applications for two minute matches.

jlindquist74 13-11-2014 14:53

Re: Electrical basics
 
Quote:

Originally Posted by Richard Wallace (Post 1400759)
(Warning: he has over 9000 posts, and the majority of them are about wiring safety.)

ObNappa: WHAT! Nine thousand! There's no way that can be right!

cgmv123 13-11-2014 17:18

Re: Electrical basics
 
Quote:

Originally Posted by jlindquist74 (Post 1408438)
ObNappa: WHAT! Nine thousand! There's no way that can be right!

It's over 10,000 now.

Munchskull 13-11-2014 20:39

Re: Electrical basics
 
I am very intrigued to see the variety of ways teams work with their connectors. My question to the teams that solider and crimp is, what type of crimping tool do you use?

cgmv123 13-11-2014 20:57

Re: Electrical basics
 
Quote:

Originally Posted by Munchskull (Post 1408478)
I am very intrigued to see the variety of ways teams work with their connectors. My question to the teams that solider and crimp is, what type of crimping tool do you use?

The proper crimping tool depends on the type of connector. For Anderson Powerpoles, there's only one crimping tool designed to crimp them properly. Other more common connectors can be crimped with several kinds of crimping tools.

Munchskull 13-11-2014 21:00

Re: Electrical basics
 
Sorry I worded that question badly. I meant to ask whether or not their teams used ratcheting crimpers.

JamesCH95 14-11-2014 08:54

Re: Electrical basics
 
Quote:

Originally Posted by Munchskull (Post 1408482)
Sorry I worded that question badly. I meant to ask whether or not their teams used ratcheting crimpers.

If you're soldering the terminal there is no need to use a ratcheting crimper since the crimp is stress-relieved from the soldering process. There are only two reasons to crimp before soldering: to hold the terminal in place and to reduce the amount of solder needed to fill the joint.

Al Skierkiewicz 14-11-2014 09:04

Re: Electrical basics
 
Munch,
We use a ratcheting crimper and then solder. Our crimper is a West Mountain Radio tool but I am sure it was manufactured by someone else and just has their name on it. It may be a better tool than the one linked above as it has terminal retention to assist in holding the terminal prior to crimp. We use a very small amount of solder. We do not want to add to the rigidity of the connection but the solder does give us a little insurance and a slightly lower series resistance.

FrankJ 14-11-2014 09:37

Re: Electrical basics
 
To anneal to soft you need to heat copper alloys to 370C plus range. Most solder for electronics melt in 183-200C range. Unless you are way over heating your joint, I don't think you are annealing of the crimp.

JamesCH95 14-11-2014 10:17

Re: Electrical basics
 
Quote:

Originally Posted by FrankJ (Post 1408548)
To anneal to soft you need to heat copper alloys to 370C plus range. Most solder for electronics melt in 183-200C range. Unless you are way over heating your joint, I don't think you are annealing of the crimp.

Well, I said stress relieving, not annealing. For annealing that number sounds correct, though I haven't looked it up any time recently.

As far as I know, which I'll admit isn't that far, most electrical-grade copper parts such as wire terminals are made from C11000 (aka 110 grade, ETP) copper. C11000 stress relieves at 180C, which as you point out is a 'minimum' soldering temperature. My understanding is that the residual stresses in a crimped connection are a significant part of what gives a crimp terminal it's good electrical and mechanical properties, and soldering heats up the joint enough to relieve those stresses.

See the google book Copper and Copper Alloys, page 252, Table 4, for stress relieving temperatures for various copper alloys.


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