Strange specs for a toroidal transformer(?) - Page 1
Forum section: electronics / general

author: x86guru
author_rank: Regular Contributor
timestamp: March 19, 2024, 08:07:05 pm
content: Hi All,So this toroidal transformer is almost 6 inches in diameter, and around 2.5 inches in height.The primary side only has one 120VAC winding and is rated at 103VAThe secondary side has two 55VAC windings @ 490VA each.I've attached a picture of the label and the size of this thing.What is going on here? Does the "103VA" primary side rating really mean that the primary side winding can only handle 850mA while the secondary windings can handle 8.9 amps each?I assume the "103VA" is either an error (maybe should be 1030VA?)I don't know the actual gauge of the windings; however, the wires coming out of the toroid are all ~16ga so I'm puzzled what is up with the 103VA primary side notation.Can anyone clear this up?

author: Benta
author_rank: Super Contributor
timestamp: March 19, 2024, 08:38:16 pm
content: ~100 VA looks about right for the physical size of the transformer.I suspect a typo. Secondaty should probaly read 90 VA, not 490.

author: x86guru
author_rank: Regular Contributor
timestamp: March 19, 2024, 08:41:52 pm
content: Quote from: Benta on March 19, 2024, 08:38:16 pm

author: BrokenYugo
author_rank: Super Contributor
timestamp: March 19, 2024, 08:45:46 pm
content: Size lines up with whatever Hammond 1kVA toroid google found me.Ohm it out? If I'm thinking right with it being near 1:1 it should have a near 1:1 turns ratio with near 1:1 resistance if wound with the same gauge wire.

author: johansen
author_rank: Super Contributor
timestamp: March 19, 2024, 08:46:19 pm
content: Yeah thats easilly a 1kva tx

author: Benta
author_rank: Super Contributor
timestamp: March 19, 2024, 08:51:59 pm
content: &%¤#"!/ Imperial units.The tape measure threw me off.

author: x86guru
author_rank: Regular Contributor
timestamp: March 19, 2024, 08:54:41 pm
content: Quote from: Benta on March 19, 2024, 08:51:59 pm-- I thought you were really that dumb

author: x86guru
author_rank: Regular Contributor
timestamp: March 19, 2024, 08:58:17 pm
content: Quote from: BrokenYugo on March 19, 2024, 08:45:46 pmI physically do not have it yet as I just bought it off eBay this morning. I'm hoping it's 980VA. I'll ohm it out and load test it when I get it. I was wondering if the 103VA was some special non-standard application. Must be an error

author: thm_w
author_rank: Super Contributor
timestamp: March 19, 2024, 09:02:29 pm
content: Quote from: x86guru on March 19, 2024, 08:58:17 pmIts not an error. The rating beside the primary winding is probably magnetization current (no load current), 103VA =1.2A.0.86AThe load rating is definitely 490VA*2.Which matches up with this post here:https://www.eevblog.com/forum/beginners/transformer-idle-consumption/

author: x86guru
author_rank: Regular Contributor
timestamp: March 19, 2024, 09:04:48 pm
content: Quote from: thm_w on March 19, 2024, 09:02:29 pmThanks, that makes sense. Except, @120v, wouldn't 103VA be 820mA?

author: thm_w
author_rank: Super Contributor
timestamp: March 19, 2024, 09:22:18 pm
content: Quote from: x86guru on March 19, 2024, 09:04:48 pmCorrect. 0.86A

author: Andy Watson
author_rank: Super Contributor
timestamp: March 19, 2024, 09:49:13 pm
content: Oh Lee Crap! Is this amateur's half-hour?It's using the same nomenclature as is used for resistors. \$103 = 1.0 \times 10^3\$, i.e. 1kVa. Which is congruent with its physical size!

author: woofy
author_rank: Frequent Contributor
timestamp: March 19, 2024, 10:03:16 pm
content: Quote from: Andy Watson on March 19, 2024, 09:49:13 pmFor resistors its not 1.0, its 10 x 10^3 =10k

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2024, 10:49:46 pm
content: What is it, AA59902055?https://hubbellcdn.com/ohwassets/HCI/Acme_Electric/Literature/SECTION-10.pdf...It's less likely to find standard parts among transformers, I mean customs are pretty common, but these ratings look standard enough. Might get lucky with a searchDon't see anything in there about primary VA though. Seems a strange way to mark it, if it's magnetization. If in doubt, I'd e-mail them.Tim

author: tom66
author_rank: Super Contributor
timestamp: March 19, 2024, 11:11:53 pm
content: Quote from: T3sl4co1l on March 19, 2024, 10:49:46 pmIronically, that datasheet has a typo on page 4 where the table lists powers from "425-800" "800-120" and "1200-1500"... perhaps the same engineer designed this transformer that wrote out that table!

author: x86guru
author_rank: Regular Contributor
timestamp: March 19, 2024, 11:32:45 pm
content: Quote from: T3sl4co1l on March 19, 2024, 10:49:46 pmIt's a AA24598C. I tried looking it up earlier with no luck.

author: thm_w
author_rank: Super Contributor
timestamp: March 20, 2024, 12:48:33 am
content: Yeah I'm probably wrong looking at it again, I see some on ebay where they listed both primary and secondary VA:https://www.ebay.ca/itm/282019280411(pri 665VA sec 625VA)https://www.ebay.ca/itm/166566676953(pri 495VA sec 480VA).So either 1030VA or 1003VA would be the number if that is the case.Which would give you an idea of the efficiency?

author: Benta
author_rank: Super Contributor
timestamp: March 20, 2024, 12:53:40 am
content: Go with the EBay specs. Everyone knows they are the most trustworthy and reliable in the world.

author: jonpaul
author_rank: Super Contributor
timestamp: March 20, 2024, 01:39:59 am
content: KW is proportional to weight.We usd e 35 cm dia 10..15 cm thick toroid's dual P-S 120/240, 5..10 kW for our client, Furman Sound.See Bel-Fuse, Pliotron, similar toroidal transformers, typical size, weight.Jon

author: x86guru
author_rank: Regular Contributor
timestamp: March 20, 2024, 02:10:10 am
content: Quote from: thm_w on March 20, 2024, 12:48:33 amI'm thinking now that AMVECO probably custom built these for another company that possibly requested the primary side be labeled with no-load current. I'm thinking this because 103VA does make sense like you previously mentioned for a no-load current and this specific model number seems to be custom and not a standard OTS available unit -- so maybe it was labeled based on a customers request.

author: x86guru
author_rank: Regular Contributor
timestamp: March 20, 2024, 08:01:10 pm
content: I received the toroidal transformer today.It has 14ga primary and secondary wires. No idea what the winding gauge is. Primary is ~.3 ohms, and each secondary is ~.2 ohms. I haven't load tested it yet, but the primary side is obviously not 103VA.Was a great deal for $25 + shipping.