The + and - "S output ports" of the CSI5003XE Power supply - Page 1
Forum section: electronics / testgear

author: sourcecharge
author_rank: Regular Contributor
timestamp: August 29, 2018, 07:51:08 am
content: Hi,I recently bought two CSI5003XE 50V 3A power supply from circuit specialists ($65/ea), and when I got it home, I tried them out.They have a output button that only puts out the supplied voltage that it's set to when this output button is enabled.I think this is nice, but..when the button is not enabled, the output on both of them is -1.7V...not sure if that is going to be a problem in the future.The current control is actually better than the more expensive PS with the same output rating, as I have both. There is a adjustment pot that can only be adjusted with a small screwdriver, and does not change when turning on and off the PS. The output control current setting is shown on the screen before the enable button is pressed, which is much better than the more expensive one that does have current control, but it does not tell you what the control current setting is, and the only way to find out is to short it.Now I use the extended ports so that I can decrease the number of banana wire connectors that I have to use. I opened up the extended port compartment, and there they were, the + and - "S output ports" right next to the + and - output ports, while in the middle is the chassis ground.Here is the link to the manual:https://www.circuitspecialists.com/pdf/CSI5003XE.pdfIn the manual there is no explanation of what these ports are, and when it was shipped, there are 2 flat fork connectors, connecting the "- output" to the "-S output port", and the "+ output" to the "+S output port". I thought they were the same output and removed the flat 2 fork connector so that I could use both screw ports for each side. But I found that the two ports are NOT the same port.There is about a 400ohm resistance between the two screw ports ( - / -S and + / +S)I have no I idea what this ports are, and maybe someone might know. I've done a search on these things but there is nothing on the net.I guess I could just leave the 2 flat fork connectors on but I'm not sure what that is doing and how they could affect anything that I am using, so I took them off.So far I have not found any problems without them, but I have them regulating only 1 amp each, and I have not actually had to use them over 10mA.Are these sensing ports? If so, why would they put them on the outside?This just doesn't make sense.Any help would be appreciated.

author: glarsson
author_rank: Frequent Contributor
timestamp: August 29, 2018, 08:20:50 am
content: These are remote sense inputs. You can use them with four wires to sense the voltage at the load instead of sending inside the power supply. This type of connection will compensate for voltage drop in the wires. When you don't need this function you install the bridging pieces.

author: helius
author_rank: Super Contributor
timestamp: August 29, 2018, 08:23:38 am
content: Quote from: sourcecharge on August 29, 2018, 07:51:08 amHave you used a power supply before? Remote sensing compensates for the drop caused by your wires. If you don't have long, thin wires connecting the load, you don't need remote sensing, so the sense terminals are strapped to the outputs to provide local sensing.I have no clue what you mean by "put them on the outside". All the accessible connections to a power supply are obviously outside it.

author: sourcecharge
author_rank: Regular Contributor
timestamp: August 29, 2018, 11:17:45 am
content: Quote from: helius on August 29, 2018, 08:23:38 amObviously, I've never used a power supply. The only things I've ever used that I thought were power supplies had at most, positive, negative, and chassis port outputs (no programable for me). I guess I have never in my life used a real power supply, but hey, learn something new everyday right?It would have been helpful if the manual had something in it explaining this function, as I have only used things that have the voltage output sense hardwired inside it. The S output ports made no sense to me because I have never heard of such a function. I was using both PS without the S outputs even connected, and they seemed to be working fine. Are we certain that this PS has this function?I looked all over the net for some type of S output from power supplies, but I could not find anything. I even asked an electronics technician about it and he didn't know about it. Are you sure this is a normal type of function that is found in "real" power supplies, where there is a sencing port on the outside?Please direct me to a link that explains this fully with a "S output" from real power supplies and how it works.ThanksEdit:Too late, I found one. Thanks again.https://community.keysight.com/community/keysight-blogs/general-electronics-measurement/blog/2018/01/25/remote-sensing-is-important-for-your-power-supply

author: glarsson
author_rank: Frequent Contributor
timestamp: August 29, 2018, 11:35:35 am
content: Again, the S connectors are inputs, not outputs.

author: sourcecharge
author_rank: Regular Contributor
timestamp: August 29, 2018, 11:42:07 am
content: Quote from: glarsson on August 29, 2018, 11:35:35 amThank you again, I was not familiar with PS with sencing inputs.Question, does the sensing inputs consume power from the power supply?

author: glarsson
author_rank: Frequent Contributor
timestamp: August 29, 2018, 12:40:32 pm
content: The whole idea with the sense inputs is that the current into the sense inputs are negligible so there will be no voltage drop on the wires connecting the sense inputs and the load.

author: tautech
author_rank: Super Contributor
timestamp: August 29, 2018, 08:50:11 pm
content: Quote from: sourcecharge on August 29, 2018, 11:42:07 amNo.Just use the PSU and one day you'll find that the voltage in what it's powering appears low and it's due to the resistance of your supply cables. That's the time you connect up the remote sense so the PSU can automatically adjust it's output to compensate for the supply cable voltage drop. Sense cables need only be light gauge.

author: technogeeky
author_rank: Frequent Contributor
timestamp: August 30, 2018, 01:23:29 am
content: Quote from: tautech on August 29, 2018, 08:50:11 pmI was waiting for someone more experienced to comment before I posted. The way I see it, there are two options for voltage sense:1. The power supply can adjust the output to compensate (up to some limitation which should be listed in the supply. Inmy supply's caseit can compensate for up to 2V of drop)2. The power supply could adjust nothing, and just report the sensed value.I am not sure if any supplies do #2, but I could see it happening. Sort of like when function generators change their displayed voltages when you select 50 ohm or high impedance output - they don't change the signal at all.

author: tautech
author_rank: Super Contributor
timestamp: August 30, 2018, 01:42:49 am
content: Quote from: technogeeky on August 30, 2018, 01:23:29 amSure but it depends on needs and wants.The new little Siglent PSU allows for VSense ON or OFF and then how much info do you want from the GUI without it adding confusion to what should a simple to use bit of kit that we all need.There'll be more info in its manual if you want to have a look:https://www.siglentamerica.com/power-supplies/spd1000x-series-programmable-dc-power-supply/