4 ms·
I use 48v for all my high power DC applications and I usually spin PCBs. Part of the reason I use 48vdc is that there are bunch of ICs and reference designs for
by samtho 3y ago
I use 48v for all my high power DC applications and I usually spin PCBs. Part of the reason I use 48vdc is that there are bunch of ICs and reference designs for PoE applications that run at this voltage level.
12v is a miserable voltage to work with in general: too high for most logic circuits and for LDOs to work effectively but it’s too low for any large load with high-power applications become cost prohibitive quickly due to the cost of the conductors. Fun fact: Auto makers have gotten away with under sizing starter conductors, despite it drawing 80-100A, because it is only energized briefly and the length of the run is very short.
- Animats 3y agoMuch industrial automation runs on 24VDC. High enough that the losses within a cabinet are tolerable, low enough that there's no electrocution hazard.
- deleted 3y ago[deleted]
- amelius 3y agoIf you keep your hands dry or if you're a male, then 48VDC can be quite safe too. https://www.allaboutcircuits.com/textbook/direct-current/chpt-3/ohms-law-again/ https://www.allaboutcircuits.com/textbook/direct-current/chp... We're running out of copper. So better keep your voltages on the high end (but still safe of course). https://www.cnbc.com/2023/02/07/there-isnt-enough-copper-in-the-world-shortage-could-last-until-2030.html https://www.cnbc.com/2023/02/07/there-isnt-enough-copper-in-...
- mbreese 3y agoTo save someone else looking for the answer to why being male is a factor here… (which I didn’t know about!) > Oh, and in case you’re wondering, I have no idea why women tend to be more susceptible to electric currents than men! The pain thresholds are given in a table that is split by men and women. I believe the assumption is different conductivity between “typical” male/female bodies, but it’s really not spelled out.
- cto_of_antifa 3y ago[dead]
- amelius 3y agoYes, on one hand it's strange because body fat decreases conductivity, and women have typically larger amount of body fat (25% versus 15%). https://www.ncbi.nlm.nih.gov/books/NBK218162/ https://www.ncbi.nlm.nih.gov/books/NBK218162/ However, men are typically larger, so perhaps that's the reason.
- ilyt 3y agoSoo fat people are more shock-resistant too ?
- gaudat 3y agoAnd I think 48VDC is the highest convenient voltage you get before exceeding ELV. There are a lot of surplus telecom and server power supplies that gives 48V at decent current. Above that there is a real risk of electrical injury, at least according to regulations.
- samtho 3y agoYou can actually go up to 120VDC (with no ripple) before you’re out of ELV - which I always find surprising. You’re probably thinking of the A/C limit which is 50V RMS.
- gaudat 3y agoInteresting, I thought the limit is at 60VDC.
- omegabravo 3y agoIEC limits are 120VDC, 50VAC which quite a few countries will use (eu*/au/nz). US NEMA/NEC is a very different standard.
- auxym 3y ago60 VDC / 30 VAC in Canada per CSA Z462 (workplace electrical safety).