Power Supply Series Mode for Split Dual Tracking Use - Page 1
Forum section: electronics / testgear

author: mawyatt
author_rank: Super Contributor
timestamp: October 08, 2024, 04:28:12 pm
content: A spin off from here:https://www.eevblog.com/forum/testgear/lab-power-supply-turn-on-and-off-characteristics/msg5669813/#msg5669813Using a PS with Series Mode (Placing CH1 and CH2 in Series for example) as a Dual Output Tracking Source is an attractive mode, useful for creating dual tacking analog supplies like +-15V for example.The Instek GPP 4324 performs this task nicely and produces CH1 + to - then CH2 + to - as a Series source with CH1 - directly connected to CH2 + for the common. This creates a CH1 +V and CH2 -V wrt to common connected CH1 - and CH2 +, thus +-V effective Tracking Supply. The GPP 4324 reads the current thru CH1 and CH2 independently and thus you can have different currents from CH1 and CH2 just like two independent supplies.The Siglent SPD3303X is different. When placed in Series Mode CH1 - to + then CH2 - to + as a Series source with CH1 + directly connected to CH2 - creating a source with CH2 + to Ch1 - with CH2 - directly connected to CH1 + as the common. However the 3303X doesn't read the current from CH2 only CH1 and displays the current for CH1 measured in CH2.Anyway, would like others to evaluate their supplies that have Series Mode wrt this type behavior.Best

author: RoGeorge
author_rank: Super Contributor
timestamp: October 08, 2024, 08:56:26 pm
content: Rigol DP832(A)has 3 channels.- Ch1 is floating, galvanic isolated from the other two channels- Ch1 can be used either in series (either with + or with - in series with Ch2) or in parallel with Ch2- Ch3 and Ch2 have internally wired common GND, but Ch3 can go up to only 5.3V, Ch1 or 2 can go up to 32V each- Any of the 3 channels can give max 3.2A, analog PS, 1mV, 1mA, SCPI, LXI, etc.- Ch1 and Ch2 can be put in following mode if needed, over current prot, over voltage prot, etc. (protection values are another setting, distinct from setting the generated V in CV mode, or generated I for CC mode). OVP and OCP are software driven (they have a small delay, and when triggered, the output channel is turned off).- Series mode is made by properly connecting the wires (manually) outside of the PS.- The PS has sense wires (leftover from another model), but they are only used internally, tied inside the PS, no sense wires are available outside of the PS- Any of the 3 channels can only be used to supply power (they can act as a load). However, with this trick it can still be used as a controlled load to measure batteries and such:https://www.eevblog.com/forum/projects/cc-cv-power-supply-as-a-contolled-load-for-batteries-(i-e-rigol-dp832)/- At best, Ch1 and Ch2 together can do +0...64V/3.2A in series, or +/-0...32V/3.2A in "anti"-series, or +0...32V/6.4A in parallel

author: thm_w
author_rank: Super Contributor
timestamp: October 08, 2024, 10:18:22 pm
content: It looks like the new SPD4000X has the same behavior as SPD3303X, no plain tracking mode just series/parallel modes only.Rigol DP932:- Voltage split across CH1 and CH2, CH1- connected to CH2+ internally, display shows the total voltage (CH1+CH2) and total current (CH1+CH2) only. Set voltage is half of the total voltage (can be a bit confusing).- Or use tracking mode: mirrors the CH1 settings to CH2 and lets you see everything independently (then add an external jumper).You can see the UNI-T 3305 behaves similarly here:youtu.be/d056TNS9aa8?t=502But the display is better, shows very clearly Series on screen.

author: tautech
author_rank: Super Contributor
timestamp: October 08, 2024, 10:34:43 pm
content: Quote from: thm_w on October 08, 2024, 10:18:22 pmSame as what, please quantify ?

author: thm_w
author_rank: Super Contributor
timestamp: October 08, 2024, 10:44:52 pm
content: Quote from: tautech on October 08, 2024, 10:34:43 pmSame as the supply OP is complaining about, SPD3303X

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2024, 01:37:16 am
content: This is a place holder for another thread that hopefully will be replicated here, we don't want to repost the thread without permission. So hold off on any specific response to this just yet as we were going to post in another thread and realized it's better for folks here.Thanks for the post.Question wrt 03_IMG20Ω (R-Blk) across CH2 shows 5V thus 5/20 or 250mA50Ω (Y-G) across CH3 shows 2.5V thus 2.5/50 or 50mA10Ω (R-Blu) across CH2 + CH3 In Series thus (5 + 2.5)/10 or 750mAYet CH2 shows 617mA and CH3 shows 546mA ??Understandthat CH2 shows Total Voltage of CH2 plus CH3 in Series Mode, thus this now becomes20Ω (R-Blk) across CH2 shows 5V but is actually 2.5V across terminals, thus 2.5/20 or 125mA50Ω (Y-G) across CH3 shows 2.5V and is 2.5V across terminals, thus 2.5/50 or 50mA10Ω (R-Blu) across CH2 + CH3 In Series thus (2.5 + 2.5)/10 or 500mASo CH2 is 125mA + 500mA, or 625mA total (reads 617mA) thru CH2 and CH3 is 500mA + 50mA or 550mA total (reads 546mA) thru CH3.Seems a little confusing as our thinking is when in Series Mode the voltage across CH2 and CH3 should beIdentical and Displayed as Suchand when taking the leads across CH2 and CH3 then this is the SUM of the Voltage on CH2 and CH3 with the Current displayed thru both as identical, and when taking the leads across CH2 this is CH2 voltage and current, when taking the leads across CH3 this is CH3 voltage and current.The GPP-4323 behaves exactly as we've described above except with CH1 and CH2 (instead of CH2 and CH3) and when setting Voltage in Series Mode only CH1 responds and CH2 follows whatever is entered into CH1.Thus CH1 is Master and CH2 is Slaved to CH1 but Voltage shown is the Voltage Across Each Channel Terminals as we would expect. Also CH2 can have the Current Limit set independent of CH1 and both Current Limits act on the Current thru the Channel, thus the lower of the two becomes the Current Limit in Series Mode forCurrents that Flow Thru Both Channelsbut still have theSame Individual Limit for Current Flowing from the Channel.Anyway, the GPP 4323 behaves exactly the way we would expect (no learning curve required) in Series Mode with Split Dual Tracking Supplies, seems the new SPD4000X may not. Curious to what you and others think about this Series Mode operation as this is a highly desirable feature for folks engaged in analog type work where like dual supplies are utilized.

author: Furna
author_rank: Frequent Contributor
timestamp: October 09, 2024, 07:59:21 pm
content: Quote from: mawyatt on October 09, 2024, 01:37:16 amFeel free to cross-quotehttps://www.eevblog.com/forum/testgear/lab-power-supply-turn-on-and-off-characteristics/msg5671025/#msg5671025Quote from: Furna on October 08, 2024, 10:04:06 pm03_IMG_20241008_235241.png posted again below; don't really like to repost but ...Quote from: mawyatt on October 09, 2024, 01:37:16 amAll correct; you summarized far better than I did. Thank you.You know ... English is not my 1st language.Quote from: mawyatt on October 09, 2024, 01:37:16 amThis my first PSU with "Series and Paralllel on a button" so at the moment I am satisfied understanding how information are presented to me. I guess I will get used to it.Indeed Voltage across CH2 and CH3is Identicalbut CH2 shows the sum while CH3 shows its own "contribution" to the total => up to observer to do the math CH2-CH3Quote from: mawyatt on October 09, 2024, 01:37:16 amOn SPD4000X while in series the "secondary" channel (CH3) is completely slaved; you cannot set Voltage neither Amps. I see the limitation that IMHO is a little one.Quote from: mawyatt on October 09, 2024, 01:37:16 amLearning curve doesn't look steep to me. I still have no idea on the "internals" and maybe this behaviour can be changed in software bu currently I do not see a reason why if not for the limitation of setting A on the "secondary" channel.Best

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2024, 09:12:17 pm
content: @ FurnaOur experience comes from many decades of in the lab use, so from a very old perspective (and individual). Recall somewhere back then we used a HP Dual Linear Supply that had a "Tracking" button that when engaged CH2 would "Track" CH1 in voltage. One had to jumper CH1(-) to CH2(+) to create a Dual Tracking +- supply which was often used for analog type work. With these jumped terminals becoming the Ground Terminal, CH1(+) the VCC Terminal, and CH2(-) the VEE terminal.This has carried thru to our expectations today and thus the "concern" wrt the behavior of the new SPD4000X series when in the Series Mode for Dual Tracking use. The SPD3303X behaves somewhat as we expect in the Series Mode for Dual Tracking with exception to the current reading display (for another discussion).The use case above with the 4000X that would be a potential problem in the Series Mode for Tracking supply use for creating +- supplies of equal magnitude but opposite polarity, like VCC and VEE with the SPD4000X series. Apparently (we don't have one and usually don't like to speculate, but this is important to clarify for potential users) the SPD4000X would produce a CH2 Display Voltage as the sum of CH3 and CH2 which would be TWICE the value of CH3 voltage output and TWICE the value of CH2, as CH2 and CH3 produce the same voltage output under this Series Mode. An unexpecting user or noob would take a look at the CH2 display reading which is TWICE the actual VCC value (and VEE magnitude) as crank the 4000X down to half the actual VCC output, thus causing the circuit under test to likely misbehave. Of course eventually the user would discover this 4000X behavior and be able to produce the correct VCC and VEE voltages and move on. So this would become a "learned behavior" required by the user wrt the SPD4000X series which might not be necessary following what we think is a more logical and historic Dual Tracking split Supply usage.Anyway, thanks for posting this and looking forward to your and others options on this.Best,

author: Furna
author_rank: Frequent Contributor
timestamp: October 10, 2024, 06:36:41 pm
content: I might be lost in translation ... you want to use an SPD4000X in Series with a second PSU (no matter what brand) to create a +- supply?

author: Furna
author_rank: Frequent Contributor
timestamp: October 10, 2024, 10:10:08 pm
content: Well if you use Series mode to connect to a different external PSU to obtain a +- supply i.e 12V set on both PSUCH2(+)SPD common groundCH2(-)SPD&CH3(+)SPD -6VCH3(-)SPD -12VCH1(-)ExtPSU common groundCH1(+)ExtPSU +12VOn SPD CH2 displays 12V and CH3 displays 6V.Still I consider this acceptable; yes a learning curve is there.

author: tautech
author_rank: Super Contributor
timestamp: October 11, 2024, 05:56:17 am
content: Fingers crossed for Mike Wyatt in Tampa that hurricane Milton only took out his power.Come back to us soon safe and sound Mike.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 12, 2024, 01:10:34 am
content: Quote from: tautech on October 11, 2024, 05:56:17 amThankfully, he's okay, but he said his power is still out.

author: tautech
author_rank: Super Contributor
timestamp: October 12, 2024, 01:20:06 am
content: Quote from: KungFuJosh on October 12, 2024, 01:10:34 amYou have contact Josh ?

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 12, 2024, 01:39:19 am
content: Quote from: tautech on October 12, 2024, 01:20:06 amYes, no power or internet yet there.

author: mawyatt
author_rank: Super Contributor
timestamp: October 12, 2024, 05:41:56 pm
content: Power and Internet backWe survived both Helene and MiltonThanks for the thoughtsBest,Mike

author: mawyatt
author_rank: Super Contributor
timestamp: October 12, 2024, 06:19:13 pm
content: Quote from: Furna on October 10, 2024, 06:36:41 pmOur use case is a single physical supply with dual (or more) independent outputs that can be configured into the "Series Mode" where 2 Channels are connected in series, like your SPD4000X and our GPP4323 and SPD3303X.In this configuration the series connection wether internal or jumper (like old HP supplies we mentioned) become the Ground and the Outputs are from one channel as +V (VCC) and other channel -V (VEE) as the 1st and 2nd channels track.Usually one expects (from experience) both channels to be same voltage magnitude and each channel should indicate the current drawn from itself. This is how the GPP4324 operates, however the SPD3303X doesn't do this as it "assumes" that CH2 is same current as CH1 and displays the current reading from CH1 into CH2 which is OK IF THE SUPPLY OPERATES IN SERIES MODE ONLY. If the supply is operating for Dual Tracking this will NOT INDICATE THE PROPER CURRENT FROM CH2!!Your SPD4000X "seems" (we don't have one so "extrapolating" based upon your comments and measurements) to operate different than SPD3303X and/or GPP4323 in that it displays the TOTAL VOLTAGE across CH2 and CH3 as the voltage on CH2 which is easily confusing (old experience), the others display each channel with it's appropriate supplied voltage accoss each terminal set (+-) as one might expect the voltage displayed on each channel as the ACTUAL VOLTAGE OUTPUT on said channel, thus CH2 displays channel 2 voltage and CH3 displays channel 3 voltage. Even if operating the SPD4000X in Series Mode only if CH3 displays any voltage this leads to potential user mistake as one might assume the total output from CH2 + Terminal to CH3 - terminal as the sum of voltage displayed as CH2 Voltage and CH3 Voltage, which would be 1.5 times the actual voltage output across these said terminals.Anyway, this is the best we can describe this condition, and from our old school perspective something that is not as expected behavior.BTW the USE of capitalization isn't for shouting, only to emphasis the importance of the core statement.Best,

author: electr_peter
author_rank: Unknown
timestamp: October 12, 2024, 07:07:57 pm
content: In Siglent PSU's series/parallel modes (based on manual) are primarily intended to double voltage/current capability and reduce wire clutter (wiring reconfigured via relays instead of externally). Tracking +/- supply (3 output terminals) is slightly different concept than two channels merged to one channel at 2x voltage (2 output terminals). I think this concept difference leads to different implementations of voltage/current displays when in series mode (one channel HV PSU vs +/- PSU).In other words, full control of +/- supply may be easier to achieve in normal (independent) mode than in series mode.

author: mawyatt
author_rank: Super Contributor
timestamp: October 12, 2024, 07:17:52 pm
content: Quote from: electr_peter on October 12, 2024, 07:07:57 pmGood points about the Intended Usage wrt the SPD3303X, as this design is much older and maybe the designers didn't anticipate the Dual Tracking Split supply use. Actually the solution is simple as they just need to implement as CH2 current reading and that's about it, maybe someone from Siglent is watchingThe GPP4323 is also an older design but implements the Series Mode exactly as we expect, measuring and showing both CH1 and CH2 Voltage and Current readings, no surprises hereThe new SPD4000X should take a serious look at how it's implemented tho, this seems like potential issues lurking as we've discussed.Best,

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: October 12, 2024, 07:43:08 pm
content: The TTI MX100TP has three outputs. It offers the following tracking modes: V3=V2=V1, V2=V1, V3=V2.Engaging these disables the voltage controls of the secondary rails. For example, setting V3=V2 disables the voltage control of V3 and it instead tracks the voltage of V2. None of these modes internally connect the terminals together, that must be done externally. In all cases, the voltage and current readings are available on all channels.I was surprised to see that with V2=V1 and a load connected to V1 causing it to enter CC mode, the voltage on V2 did not drop to match V1. Therefore, it's not a true 'tracking' supply, but one where the setpoints are matched.The supply also offers several of ranges, some of which internally connect the three channels in series or parallel. One can get 16V/6A, 35V/6A*, 35V/3A, 70V/1.5A, 70V/3A*. The ranges marked with a * internally connect the channels. Voltage/current readouts are hidden for channels that are 'lost' due to the paralleling.