psu power ratings - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: April 24, 2022, 12:38:53 pm
content: hi,just thought i would ask,are linear power supplys built higher than they are rated for current wise,my 10a linear psu has a torroid about 3.5 inches deep and 6 inches dia,this seems large for just a 10 rating.

author: IanB
author_rank: Super Contributor
timestamp: April 24, 2022, 01:04:34 pm
content: "Just a 10 amp rating" is a weird thing to say. 10 amps is a huge current for a laboratory PSU.

author: m3vuv
author_rank: Super Contributor
timestamp: April 24, 2022, 01:53:19 pm
content: i didnt need to kow if its wierd question,how about if you dont know the answer to my question and cant help dont comment!

author: BrokenYugo
author_rank: Super Contributor
timestamp: April 24, 2022, 02:04:34 pm
content: The most expensive part isn't going to be oversized. VA rating drives the core size, not amps.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: April 24, 2022, 02:25:15 pm
content: A 1000 volt amp toroid transformer is about this size apparently, look down this link on page four and find one about your size:https://www.hammfg.com/electronics/transformers/power/1182.pdf

author: gnif
author_rank: Unknown
timestamp: April 24, 2022, 02:31:02 pm
content: Quote from: m3vuv on April 24, 2022, 01:53:19 pmOnce again, how about you settle down and stop snapping at people, this is a public forum, nobody is obligated to answer your exact question, and everybody is allowed to comment on your question. Why are we still trying to get you to understand this?

author: m3vuv
author_rank: Super Contributor
timestamp: April 24, 2022, 02:52:55 pm
content: Quote from: gnif on April 24, 2022, 02:31:02 pmYou ask why,maybe because people still dont get it,let me make it clear to everyone who wants to reply,if you cant help with the specific question/questions i ask "DONT COMMENT!!!!" is that clear enough?.

author: m3vuv
author_rank: Super Contributor
timestamp: April 24, 2022, 02:59:09 pm
content: just had a look at the link wallace,i get the impression for the same v/a ratings a torroid is bigger than an I/E core?

author: gnif
author_rank: Unknown
timestamp: April 24, 2022, 10:40:41 pm
content: Quote from: m3vuv on April 24, 2022, 02:52:55 pmThis is not your forum, nor is this how forums work. YOU are wrong, not the people commenting here. YOU can ignore these comments if they don't apply, it's that simple. Is THAT not clear enough?Of the 55,553 members here, YOU are the only person making this complaint... what does that say to you?If you're not happy with this, find another forum that operates exactly as you demand it to and go there.

author: sahko123
author_rank: Frequent Contributor
timestamp: April 24, 2022, 11:43:42 pm
content: You shouldnt get angry at people trying to get a clarification on your question because they are trying to help answer it.Yes power supplies might be able to output higher currents than their rating but generally would be limited to that rating to make sure no damage occurs. Transformer size relates to power not current. The bigger a mains transformer is the more power it can supply. So for example if the power supply is rated for 10A at 24V you would get 240W and the transformer might be rated for 300VA to be account for in-efficiency

author: bdunham7
author_rank: Super Contributor
timestamp: April 25, 2022, 02:34:50 am
content: Quote from: m3vuv on April 24, 2022, 02:52:55 pmSir, this is EEVBlog.QuoteNot typically AFAIK. I have some linear PSU carcasses (Tektronix by GWInstek) that have about 160W total DC output and the EI core transformer is about as big as you say yours is, maybe a bit smaller. The unit says "300W 386VA" on the back. So if you have a 320W DC output PSU, you figure in a similar low-ish efficiency and average-to-RMS current ratio and you are looking at maybe ~600W and 800VA maximum input. So a 1kVA-sized transformer isn't surprising. EI transformers of that size are 6-7" cubes and weigh 25-35lbs.

author: mikerj
author_rank: Super Contributor
timestamp: April 25, 2022, 03:15:09 pm
content: Quote from: m3vuv on April 24, 2022, 02:52:55 pmYou regularly ask for help and then immediately get your knickers in a twist when someone points out an issue. This is a "you" problem, no-one else's.Transformers are rated in VA; you have provided the current your linear supply can deliver, but not the voltage.

author: not1xor1
author_rank: Frequent Contributor
timestamp: April 25, 2022, 04:09:38 pm
content: Quote from: m3vuv on April 24, 2022, 12:38:53 pmThe size of the transformer is related to the power (VA).The size (section) of the wires used in the windings is related to the current.So your question is nonsensical.