Power Supplies in Parallel  - Page 1
Forum section: electronics / beginners

author: staticshock
author_rank: Contributor
timestamp: August 15, 2024, 08:41:12 pm
content: I have a set of 5 40V power supplies (call it SetA) that are connected in parallel and another set of 5 400V power supplies (call it SetB) also in parallel. Each set is connected to a terminal block. Currently SetA is connected to TB1 and SetB is connected to TB2. Both TB are being supplied by 480V. Is this setup correct that all power supplies in each set is being connected together to the same source?Does it matter if for some reason I had 2 power supplies from SetA connected to TB2 instead and 2 power supplies from SetB connected to TB1 instead?

author: indeterminate
author_rank: Regular Contributor
timestamp: August 15, 2024, 10:20:50 pm
content: ProbablyWithout knowing why it is wired up like this and the surrounding circuitry it is not possible to know the effect of the change.

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: August 15, 2024, 10:42:34 pm
content: We're talking about connecting theinputsof the power supplies to the terminal blocks? If so, it shouldn't matter as long as there's enough voltage and current on the terminal blocks.If we're talking about power supplyoutputsbeing connected in parallel, that's a different matter.

author: staticshock
author_rank: Contributor
timestamp: August 16, 2024, 05:52:34 pm
content: I edited my question.The first set of power supplies are all 40V and the second set are all 400V. Does that change the situation?

author: tooki
author_rank: Super Contributor
timestamp: August 16, 2024, 10:24:34 pm
content: Quote from: staticshock on August 16, 2024, 05:52:34 pmAnswer Melt-O-Tronic’s question. It’s not really clear what your question is. And your diagram is too small to read.

author: indeterminate
author_rank: Regular Contributor
timestamp: August 17, 2024, 05:39:20 am
content: are all 40V and the second set are all 400V. Does that change the situation?yeseverything changes the situation.what happens when i wont to work on the equipment connected to 400v and i switch off the cb feeding TB2changing sh*t like this is what causes major outages / deathyou need to look at the entire system and why it was built this way in the beginning

author: tooki
author_rank: Super Contributor
timestamp: August 17, 2024, 11:09:29 am
content: Quote from: indeterminate on August 17, 2024, 05:39:20 amPlease use quote tags (either manually or by using the Quote buttons on posts) to demarcate your responses from the questions you’re responding to. Your style here of using no formatting (not even quotation marks!) is unnecessarily hard to follow.

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: August 17, 2024, 03:24:53 pm
content: You never answered me so it's still not clear whether you're talking about the power supply inputs or the outputs. But if you're tying a 40V source directly to a 400V source, you're going to have some problems that have nothing to do with the power supplies or the terminal blocks.What,exactly, are you trying to accomplish? Your "question" makes no sense to me.

author: staticshock
author_rank: Contributor
timestamp: August 20, 2024, 06:16:27 pm
content: I apologize for any confusion and the diagram was too large so I resized it. I'll try to be more clear.There is a 480V 3 Phase coming in to a system. The 480V is split to energize two terminal blocks (TB1 and TB2) on the back of the system. Each terminal block has 6 posts. The 480V is further split, where Phase A goes to post 1, Phase B goes to post 2, Phase C goes to post 3, and an identical setup for A/B/C to 4/5/6 respectively. TB1 is suppling an input to power supplies SetA and TB2 is suppling an input to power supplies SetB.In SetA, power supplies A1/A2/A5 are connected to posts 4/5/6 and power supplies A3/A4 to posts 1/2/3.In SetB, power supplies B1/B2/B4/B5 are connected to posts 1/2/3 and power supply B3 to posts 4/5/6.From this setup, we can see that all of SetA (40V power supplies) are connected to one terminal block and all of SetB (400V power supplies) are connected to the other terminal block. My question again, is this correctly wired since all of the 40V power supplies in parallel are tied together and the same for all of the 400V power supplies in parallel are tied together?I have some uncertainty because both terminal blocks are still being supplied by one 480V 3 Phase that has just been split. That is why my second question asks if it makes a difference if for some reason one of the power supplies from SetA was connected to TB2 or one from SetB was connected to TB1 even though all paths trace back to the same 480V 3 Phase.

author: Melt-O-Tronic
author_rank: Frequent Contributor
timestamp: August 20, 2024, 08:51:54 pm
content: OK, since you're talking about the inputs to the power supplies, it really doesn't matter what the power supply outputs are. What matters is that they all get adequate input voltage and current. When you tie a bunch of terminal blocks to a common source, they're all effectively one power rail, so the number of power supplies you connect is of little consequence.It sounds like you could hook up as many power supplies at whatever output voltages you want, so long as 1) they're all getting the voltage and current they need and 2) the rails (blocks) are suitable to safely carry that current.Edited to add: If you're also connecting the power supplyoutputsin parallel, you may need some additional consideration there to ensure even load sharing.