Is this module isolated? - Page 1
Forum section: electronics / projects

author: klr5205
author_rank: Regular Contributor
timestamp: May 01, 2018, 02:51:44 pm
content: Second guessing myself here...This datasheet calls out a 4kVAC isolation voltage, but I don't see a block diagram or anything that gives me a warm fuzzy feeling that the input is truly isolated from the output. I wouldn't want any nasty surprises when it comes time to hook the thing this is intended to power up to a PC...https://www.recom-power.com/pdf/Powerline_AC-DC/RAC10-K_277.pdf

author: David Hess
author_rank: Super Contributor
timestamp: May 01, 2018, 03:20:41 pm
content: It gives full isolation specifications on page 4 so it is isolated.

author: nctnico
author_rank: Super Contributor
timestamp: May 01, 2018, 04:09:21 pm
content: It is isolated. What is important to look out for are the third party safety approvals if the isolation needs to offer safety (like seperating a mains power part from a low voltage part of a circuit). There are lots of isolated modules out there with similar isolation specs but some don't have the third party safety approvals.

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 01, 2018, 04:38:02 pm
content: It is. On page 5 you have the safety standards it complies with. You can check these out to make sure it will meet your requirements.Since it's an AC/DC converter, and it's clearly designed to be connected to mains, they don't explicitely mention in the description that it is isolated. It's more common to see this mentioned for DC/DC converters when it applies.

author: IDEngineer
author_rank: Super Contributor
timestamp: May 01, 2018, 10:23:28 pm
content: Quote from: SiliconWizard on May 01, 2018, 04:38:02 pmNever forget there are different definitions of "isolated" too. Galvanic isolation is great for protecting people, but that doesn't mean it's isolated in all other senses. We evaluated a bunch of DC-DC modules last year for a project that needed TRUE isolation for a subsection of its circuitry, and there wasn't a single one that was truly isolated. Look up "isolation capacitance" for just the very start of this Alice in Wonderland rabbit hole. We ended up having to cook our own power supply design to get the required isolation.

author: SiliconWizard
author_rank: Super Contributor
timestamp: May 02, 2018, 08:37:40 am
content: Quote from: IDEngineer on May 01, 2018, 10:23:28 pmQuite right. Most "isolated" off-the-shelf DC/DC converters are isolated to comply with some safety standards, usually to protect people indeed.An interesting fact in the same vein is that you can sometimes see power supply sections with isolation for safety reasons that have additional discrete capacitors across the isolated grounds. Works for safety, but may cause a whole lot of other issues, such as bad crosstalk issues between isolated domains.

author: klr5205
author_rank: Regular Contributor
timestamp: May 02, 2018, 01:36:46 pm
content: Thanks for the peer-check guys. Like SiliconWizard alluded to, I'm so used to seeing isolation being mentioned in the "marketing wank" of DC/DC converters when it applies that it made me second guess myself about this particular part.Good notes about the isolation capacitance btw!