3000DT-VA Step Up/Down Transformer Spec Confusion - Page 1
Forum section: electronics / projects

author: bostonman
author_rank: Super Contributor
timestamp: February 29, 2024, 04:40:58 am
content: Recently I got a "broken" 3000DT-VA Step Up/Down Transformer. It has a line voltage selector switch on the rear, a push button "fuse" (as it's marked - although I know this is a circuit breaker), and a circuit breaker on the front panel that's used as the on/off.Tracing the 120v line, the hot comes in, goes into the line voltage selector switch (selected for 120v), the 120v connections go out of the switch and into the front panel on/off switch, and out to the receptacle on the front panel. The neutral goes back to the input connector.I found the line voltage selector switch was open causing the unit to not turn on (which was the reason it was tossed in the trash at my job). The line voltage switch and the front panel switch are in the links below.My first question: the line selector switch is rated for 10A at 120V (and this is stated on my switch). If the unit is 3000VA, even at 50% efficiency, that's 12.5A. Why would a 10A switch be used? I disassembled the switch and it clearly had burn marks on the terminals.I'm uncertain if this switch will be a good replacement. It looks identical to the one I have, however, the dimensions differ. Assuming the dimensions are the face and not the body, and the other dimension is the overall depth (not including terminals - but face to bottom where the terminals exit), mine is: 42.2mm x 14.6mm x 12mm. Ideally I'd like to replace this with a more robust switch since it's only 10A, but not sure another will fit.The other question is about the front panel switch/breaker. I know it's rated for 63A (per the description), but why does it have 4500A on the front (implying it's 4500A - which I know it's not).? Also, is the 230 DC voltage and 400 is AC?https://www.amazon.com/uxcell-Terminals-Voltage-Selector-Switch/dp/B01N9SG68V/ref=asc_df_B01N9SG68V/?tag=hyprod-20&linkCode=df0&hvadid=343224601369&hvpos=&hvnetw=g&hvrand=10124679596826294573&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9001771&hvtargid=pla-690946710715&psc=1&mcid=5137aed0a12631389a7ee5a1e9ecf1b7&tag=&ref=&adgrpid=70737352522&hvpone=&hvptwo=&hvadid=343224601369&hvpos=&hvnetw=g&hvrand=10124679596826294573&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9001771&hvtargid=pla-690946710715&gclid=EAIaIQobChMI49O40tfPhAMVk2hHAR3SqALJEAQYAiABEgI8LvD_BwEhttps://www.amazon.com/MariaP-DZ47-63-Overload-Protection-Circuit/dp/B078H15M26

author: moffy
author_rank: Super Contributor
timestamp: February 29, 2024, 07:15:30 am
content: Quote from: bostonman on February 29, 2024, 04:40:58 amThe 4500A is possibly the maximum fault current that the breaker can break reliably, the 63A refers to the trip point of the breaker not its maximum fault current capacity. A DC and AC voltage rating is quite common with the AC being higher because it is more difficult to break a DC arc than AC which has natural 0V transitions twice a cycle.

author: bostonman
author_rank: Super Contributor
timestamp: February 29, 2024, 05:27:29 pm
content: After calling it a night last night, I thought more about the line voltage selector switch. Maybe it's 10A per rail because the design ties pins 1 and 2 together, 3 and 4, etc.. So in total, the switch can handle 20A.Either way, the switch fried a bit which is the cause of the unit not working.