terminal block current rating - Page 1
Forum section: electronics / projects

author: brumbarchris
author_rank: Regular Contributor
timestamp: August 04, 2016, 11:21:07 am
content: So is the 12A current rating (indicated on page 2 in the datasheet from the link below) valid for each pin individually or is it valid for the entire connector?http://media.digikey.com/pdf/Data%20Sheets/Phoenix%20Contact%20PDFs/1755736.pdfThanks,Regards,Cristian.

author: Blastcap
author_rank: Regular Contributor
timestamp: August 04, 2016, 12:20:42 pm
content: Per pin.

author: brumbarchris
author_rank: Regular Contributor
timestamp: August 04, 2016, 12:25:41 pm
content: Is it a general standard for all those terminal blocks to refer at pin only? I am asking because since I posted the original message I reviewed several datasheets of similar connectors and none of them explicitly indicates if the current rating is referring to the entire connector or just to one pin. So I guess it is the "industry standard" or "generally accepted" that it is per pin...?Regards,Cristian

author: MagicSmoker
author_rank: Super Contributor
timestamp: August 04, 2016, 12:41:25 pm
content: The current rating is always per pin. Or, at least, I'm not aware of anyone who specifies it differently.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 04, 2016, 01:28:39 pm
content: If it's a power connector total current would be 0 A for the full connector. (10A in, 10A out)Not a really helpful spec.

author: CM800
author_rank: Frequent Contributor
timestamp: August 04, 2016, 02:31:56 pm
content: Quote from: Jeroen3 on August 04, 2016, 01:28:39 pmThat's kind of a cheeky response there. Obviously that would be the case, however you could look at it from the logical perspective of "sum absolute currents through the pins" which would be 20A.I have seen some connectors specify a lower current rating the more the pins on the connector.After all, the amount of current a connector can handle is linked to the resistance across the connector pin-collection and how well it disspates said heat.Either way, It's always rated per pin.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 04, 2016, 02:46:46 pm
content: Another easy way to see that it is per pin is when you see that they spec the same for the full family. From 2 to 16 pins.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 04, 2016, 09:42:06 pm
content: Be careful.The rating is usuallyper pin, with no other pins energized.For example, cheap 0.1" headers are rated for 2-3A -- individually. A 20-pin header can't carry a total of 40-60A*. It's less than half that.*Which, in a real application, would be 20-30A, half for plus and half for minus.Read the datasheet carefully. If it doesn't specify, contact the manufacturer, and insist that they properly document their specifications!Tim

author: brumbarchris
author_rank: Regular Contributor
timestamp: August 05, 2016, 05:25:39 am
content: QuoteIt seems indeed, that is the case! I've looked the problem more in detail and I came across (among others) this article:http://powerelectronics.com/content/demystify-current-ratings-connector-selectionCheck out the first few sentences in the Derating Contacts section. It says: "Published current ratings in catalogs are often for a single contact pair isolated in ambient air. This is an ideal and artificial situation."The key word here is "often", and I agree, the best way to be absolutely sure is to get a statement from the manufacturer of the said pin.Or just switch to using single pin connectors...Regards,Cristian

author: ajb
author_rank: Super Contributor
timestamp: August 05, 2016, 04:19:56 pm
content: There may also be different ratings for wire-to-board, wire-to-board, and board-to-board matings, if the connector family provides for those configurations. Hopefully the manufacturer will specify if there's an appreciable difference. I saw a datasheet recently--from Molex, maybe?-- that flat said something to the effect of 'current ratings are guidelines only and real world limits are up to the user to figure out', which is unusually candid.

author: nctnico
author_rank: Super Contributor
timestamp: August 05, 2016, 04:32:13 pm
content: The best thing to look for is some data on how the pins are derated versus ambient temperature. Another question is how much current you can allow through the solder joint and through the PCB traces.