duncanampspsud@groups.io

Fw: All sorts of bother...

[email protected]

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On Tuesday, October 20, 2020 12:49 PM, neutron51493 <neutron51493@...> wrote:

Hello

A life-long Apple user I now have a MacBook Pro (which, incidentally, I really do not like) running Catalina 10.15.7 (latest incarnation) on which I have attempted to download PSUD2 on a number of occasions ~ and, as with the reports of other potential users, with little inner standing…

Rather stupidly I’ve come to realize I was attempting to enlist its help to replace?5ц3с?rectifier valves in a "standard Sun Audio 300B type CLC PSU ~ with Vishay Hexfreds (HFA16PB120HN3) which are 16A 1200Vr types purchased some years ago... and I'm completely out of my depth.

Today I did manage to override the OSX security warnings (not a recognised developer etc) and managed at least a "look-see" - and to my horror found I would probably fry similar? 1200Vr IXYS diodes. ?Do we?really?need 1800Vr (!?) I couldn’t answer that because,

no matter what I did subsequently the “security" would?not?allow PSUD2 to run ~ it came up with another error message about some rectifier or other not being found :-

Utilisling the programme is certainly not without difficulties and as others have suggested some more guidance would be very helpful. ?Otherwise this old Chemistry kid with a very old A level Physics experience and a new soldering station will need to copy established designs - e.g. Dr Jac van Der Walle’s ~ or see expensive things go up in frightening smoke - which is I suppose entirely the reason why such guidance isn’t provided for novices such as myself?
Have I answered my own question as far as that aspect is concerned ?

Siobhan

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Screenshot 2020-10-20 at 12.13.32.png

Re: Error occurred floating point overflow

#15

I think the problem might be in the rectifier file. I've noticed it has a very high VLaw value (81) which doesn't look right and may encourage numeric overflows.

rect

type

dres

vlaw

vfac

vpiv

ipks

ipkr

name

email

ip

approved

trash

created

Cree SiC C4D02120A

SS

1.85

81

1.4

1200

19

13

1

0

29/03/2014 11:31

It was always the case historically that people could upload their own rectifier models to the website, however this has led to some models with bizarre values in that can throw an exception. I've stopped that a couple of years ago and removed 31 rectifier models which had values in that clearly could not work. Some (like this one) were borderline so I left them in.

Ongoing, on PSUD3, the only rectifier models that will get issued with the software are ones that I will have hand-checked against data sheets and signed off. This won't stop people adding or reusing their own models in the privacy of their own homes, it will just stop untested models getting into the core distribution and give those who don't dabble in the models to have a safe and consistent platform to work from.

Hope this explains what might be going on here and what is being done to sort it out.

Regards,
Duncan

Re: Error occurred floating point overflow

#14

In PSUD 2.1 build 63 on Windows 7, Adam's oops.psu file throws an error on loading. Help does nothing. OK shows numbers, all 10000M.

The circuit looked OK but I never saw the SiC rectifier. On a hunch I changed to generic Bridge-1000. This runs fine as expected.

oops-psu-42.gif

oops-psu-2-42.gif

Re: Error occurred floating point overflow

[email protected]

#13

Duncan, thanks for the quick reply. Currently using Win 7 here. Did some testing and its four models out of the list that produce the error.?

C4D200330D
C4D02120A
C4D05120A
CSD20030D

Very strange.

Re: Error occurred floating point overflow

#12

Hi,

I've tried the sample file on V 2.20 build 74, can't see anything problematic in it, and it runs OK. I'm using Windows 10 for the test. For info, what operating system are you using?

Regards,
Duncan

Error occurred floating point overflow

[email protected]

#11

Getting the above error when trying to run this simulation. Version 2.20 build 74. Thanks.

oops.psu

Re: Transformer current high with full-wave

#10

There is also a nice description about that at the ValveWizard's page:?

UI suggestions

#9

1. PLEASE follow the current / last doc path for File -> Save As. Navigating a directory tree for each revision is silly.
2. PLEASE make the app open in the same location as when closed. Opening in the of the virtual space with multiple monitors is even sillier.?

Thanks for a? G R E A T? app!

Re: Transformer current high with full-wave

#8

The only way I can think to do that is to work out the average transformer current, however this will always equate to zero over a period of time as each half-cycle will cancel the other.

One example of the way the transformer average current could be worked out is to do a reporting delay of 1 second to let everything stabilise then do a simulation for just half of a mains cycle to prevent cancellations. If you do this, the average transformer current is 150mA which ties exactly with the links you posted showing IAC = IDC.

However, the RMS current in the transformer (which is what makes it hot) is around double this, the reason being that the rectifiers are only conducting for part of the half cycle.

I'm guessing that this difference is "baked in" to the transformer margins as they know the intended use of say a 350-0-350 transformer will be a capacitor input supply of some type where RMS > Average. A choke input will give RMS and average numbers closer together due to the longer conduction angle.

Regards,
Duncan

Re: Transformer current high with full-wave

#7

I understand what you're saying.
I wonder though how one could utilize this software to assist in determining ac current requirements for a power transformer?
Or are you saying that this higher rms current output is indicative of how a power transformer should be rated for a rectifier like this?

I just noticed that Sowter, and Hammond both indicate that Idc = Iac with a full-wave capacitor input configuration.

Re: Transformer current high with full-wave

#6

Thanks for the attachment, I had a look and can now explain the different numbers.

The current in the transformer is through the winding and for both directions. Let's say the RMS value is X and the average will be zero or near-zero.

The current in the rectifier is for one half cycle, the RMS value will actually be X/SQRT(2). This seems counter intuitive because you think it would be half, but that's not the case - it's really 70.7%.

I even had to convince myself, and made up an Excel spreadsheet to step through some example numbers to check it out (attached).

Part of the problem here is that a full suite of min/max/diff/avg/rms is provided for all points and while some of the numbers are useful (i.e. max and average for a rectifier), some of the results like RMS current in a rectifier are of limited or dubious value in the real world. Whereas in a capacitor, it's a very useful value to have.

Hope that explains the background and why the numbers are not what you would intuitively expect - I'll put a "health warning" in the documentation about this.

Regards,
Duncan

joel_845ps.xlsx

Re: Transformer current high with full-wave

#5

Okay, I added the psu file here. I tried it with the latest build (75) and saw the same behavior.
I'm running on Windows.

845ps.psu

Re: Transformer current high with full-wave

#4

Hi Joel, could you post the .psu file here as an attachment? (hope that's possible, the forum is quite a new venture and still finding my way around it)

Also if you could let me know which version you are using; Mac/Windows, also the build number from Help|About.

Regards,
Duncan

Transformer current high with full-wave

#3

Someone posted on Diyaudio about this, but I'm seeing the same thing - with a typical full wave rectifier circuit I'm seeing higher RMS current in the transformer than I think I should be.
With a 150mA load, I see 220mA RMS current in D1, and 312mA in T1.

PSUD2 Build 75 released

#2

Build 75 has been released today and is available from the files area: /g/duncanampspsud/files/

Changes:

Enhancements to UI to better support dark mode on macOS
Improved handling of column widths on the results area, on both auto and manual column sizing

Welcome to the group

#1

Welcome to the 开云体育 area for the Duncanamps PSU Designed (PSUD). This is a place to ask questions about the usage of the product, report issues with the software and find out about what's coming up in the future.

The current offering is PSUD2 which allows simple linear power supplies to be modelled using a single phase transformer paradigm. The software doesn't cater for regulators, switched mode or anything like that - please check out the excellent if you wish to dabble in more advanced power supply modelling.

PSUD(2) has been around for 21 years now and that's a long time in the software world. As of June 2020 there is a PSUD3 in the works, it will still have the same simple "world view" of PSUD2 so it's not intended to do much new, just do it better.

Some of the key things in the plan for PSUD3:

More accurate simulator
Vector graphics to take advantage of higher screen resolutions of today
XML file format for power supplies which can store chart selections, colours, etc.
Rectifier modeller
Monte-Carlo simulations
Mathematical functions
Aggregation functions
Windows / Linux / MacOS 64 bit application

There isn't an ETA for PSUD3, I've been diverted writing some of the technology to support it and it's not my day job but it will show up one day :)

Regards,
Duncan