Dc clamp meter community inrush test - Page 1
Forum section: electronics / testgear

author: Fiveohfour
author_rank: Contributor
timestamp: December 05, 2018, 02:38:43 am
content: I’m hoping to crowdsource an effort to check all the common clamp meter brands that do dc and have the inrush function and test to see which of them if any are able to measure DC inrush.I hear so many referred to as fluke clones, but Fluke Clamp’s can measure DC inrush, yes I know their data sheets might lead you to think they can’t, but they can, and the documentation is being updated in the not distant future.For now, I’m wondering how many other brands , especially the clone types, are able to do so, even if they don’t know they canSent from my iPhone using Tapatalk

author: eKretz
author_rank: Frequent Contributor
timestamp: December 05, 2018, 02:56:32 pm
content: Wouldn't this be any amp clamp with a min/max function?

author: BravoV
author_rank: Super Contributor
timestamp: December 05, 2018, 03:09:58 pm
content: What do you mean by "inrush" current ? For how fast ?If you're talking about ordinary clamp meter (assuming not those 4 digits priced oscilloscope's DC current probe), personally I never see the words "inrush current" measurement capability. Only min/max as eKretz pointed out above.Btw, I do own Keysight U1213A clamp meter capable of DC current measurement (=>Teardown here) , and Kyoritsu KEW 2300R which is a NCV (Non Contact Voltage) detector and DC/AC current "fork" tester, photo below. No such feature on both.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: December 05, 2018, 03:42:41 pm
content: The fluke 375 / 376 and remote display 381 can do inrush as well as max / min. Different functions because inrush is a quicker sample. I don’t know how quick the inrush setting is, but it’s been good enough for me in the past. Max / min doesn’t catch the inrush properly.

author: Fiveohfour
author_rank: Contributor
timestamp: December 05, 2018, 04:12:01 pm
content: Quote from: PTR_1275 on December 05, 2018, 03:42:41 pmI’ve spoken with the engineers from Fluke and a couple of other companies. Best as I can tell fluke spearheaded a standard for inrush measurement functionality. It takes a bunch of samples within a 100ms window that begins at the moment you press the button. Agree max/min often just won’t work for this accurately.this allows you to know the true starting current of a motor for example, which can be many times higher than even the max reading.Bottom line is inrush function captures a window of data with many samples taken in it, max/peak functions are a single sampleFluke has a video on YouTube explaining the implementation of max/min/peak testing and finally the inrush feature that they developed with a handful of other industry players iircAnyhow given how many “fluke clones” are out there, I’m wondering if any cheap clones have a Easter egg feature so to speak.Last thing, this isn’t “new”, but I guess it’s a more recent featureSent from my iPhone using Tapatalk

author: Fiveohfour
author_rank: Contributor
timestamp: December 05, 2018, 04:37:34 pm
content: Quote from: BravoV on December 05, 2018, 03:09:58 pmIt’s more typical of the higher end offerings. Though it’s trickling down. All 3 fluke clamp testers offer it, though the bottom end is AC only. The Uni-T & Mastech & Extech and all those brands higher end ~400-2,000 amp max units tend to have inrush functionality. I don’t recall if I found any keysight meters that do, they all seemed in need of updating.Sent from my iPhone using Tapatalk

author: macboy
author_rank: Super Contributor
timestamp: December 05, 2018, 07:17:01 pm
content: Quote from: BravoV on December 05, 2018, 03:09:58 pmHmm... you are wrong about the Keysight. I owned one of those briefly, and I know it has such a feature. From the features list on page 21 of the manual, "1 ms peak hold to capture in-rush voltage and current easily.". This is very different from plain old min/max functionality, as that will typically store the minimum or maximumreadingwhich is not necessarily apeak, since each reading is integrated over approximately 1/(reading rate) or at least a few hundred milliseconds. The 1 ms peak hold can, as it implies, capture a peak lasting only 1 ms.

author: tautech
author_rank: Super Contributor
timestamp: December 05, 2018, 08:56:06 pm
content: Quote from: Fiveohfour on December 05, 2018, 04:12:01 pmDoesn't matter much if you have the proper curve (C or D) motor rated breaker installed.What matters more for motor work is the run current is within label limits.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 06, 2018, 01:41:03 am
content: I am also a bit confused about what the inrush would mean without knowing something about the expected wave shape.I guess for DC, 50+A with 100KHz, I would use a DSO and LEM sensor. For ampish, my vintage Tektronix P6042 and again a DSO. I have a fair number of shunts that I could amplify the signal and drive the DSO but you want a clamp. I did manage to get about 100KHz 3dB out of my disposable UNI-T UT210E clamp and have an analog output to drive the DSO. It works pretty good for what it is. For work, the HIOKI I use can measure down to DC and can sample up to 2MHz. You can install up to four clamps. It does a good job but comes at a price.I can't see a simple peak detect being very useful.

author: Fiveohfour
author_rank: Contributor
timestamp: December 06, 2018, 03:15:02 am
content: Quote from: macboy on December 05, 2018, 07:17:01 pmYea peak/also called peak min/max is different than min max & much faster but again it’s not the same as an inrush measurement function, there’s a reason literally every clamp meter of a certain value has both features. The peak function was developed to help gauge inrush but the inrush measurement function was eventually able to be properly integrated into handheld clamp meters.Watch this video, it shows you the Peak & Inrush measurement simultaneously, they’re different values.https://youtu.be/P0Ho_va9Lk0And here is Fluke discussing ithttps://youtu.be/2xIsmRkpQLANevertheless, while I appreciate everyone’s attempts to explain why I don’t need it or it’s the same as the peak function etc, my original question/aim is the point here, namely I’m hoping those who have meters with a proper inrush function will test to see if it works on dc or not. (not a meter with peak who’s manual says to use it for inrush because it was made before the inrush function was around)I’ve got a handful of higher end brands who’s inrush measurement works with dc, wanting to find some moreSent from my iPhone using Tapatalk

author: Fiveohfour
author_rank: Contributor
timestamp: December 06, 2018, 03:21:44 am
content: Quote from: joeqsmith on December 06, 2018, 01:41:03 amHandheld clamp meters are what I’m after currently, and as mentioned just before it’s a little different than peak min/max. If I had a bench full of nice gear I would be interested in using it in this way but I’d still be interested in determining what handheld clamp meters with an inrush function have the ability for it to be used with DC current, and since the manuals aren’t trustworthy I figured it was worth trying to crowdsource an experiment and compile a list so anyone looking for the same won’t be forced to buy the top of the line tools or assume no handheld clamp can do it at allSent from my iPhone using Tapatalk

author: The Electrician
author_rank: Frequent Contributor
timestamp: December 06, 2018, 06:18:52 am
content: Fluke defines inrush current as the current occurring during a 100 mS interval:http://support.fluke.com/find-sales/Download/Asset/1629920_6115_ENG_B_W.PDFHioki has a more flexible measurement:http://hiokiusa.com/wp-content/uploads/pdf/28674-CM4370_en.pdfWhat would be the definition for DC inrush current?

author: Fiveohfour
author_rank: Contributor
timestamp: December 06, 2018, 07:29:27 am
content: Quote from: The Electrician on December 06, 2018, 06:18:52 amits more accurate to say that’s how they define their inrush measurement function, but yea dc inrush could fit into both approaches, whether the it can still make a valid calculation or can take into account different waveforms and whatnot is another question.For now i have the same question and would like to see how the fluke 376 or any model with a proper inrush function reports dc results, how that compares with peak/max min will tell us a fair amount id imagine.Depending on the answer I’d then hope someone with a fancy power analyzer like the keysight below can compare the two.Sent from my iPhone using Tapatalk

author: The Electrician
author_rank: Frequent Contributor
timestamp: December 06, 2018, 07:36:58 am
content: What would you like the reported DC inrush for the shown waveform to be?

author: The Electrician
author_rank: Frequent Contributor
timestamp: December 06, 2018, 08:30:26 am
content: The video you linked:shows the DC starting current in an automobile, and gives two results for current 518 amps (peak?) and 354.5 amps (inrush?)Another video shows what appears to be the same auto starting with a clamp meter used as a current sensor:Here we can see the current waveform. This may give a clue as to what Hioki is doing to get the 354.5 amp value. Probably some kind of average.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 06, 2018, 12:13:08 pm
content: I didn't see any equations in these videos about how they derive these numbers or if there are industry standards. It's hard to believe that there would be with an infinite number of shapes.I assume you would want this for calculating wire gauge, connectors, fuses, CBs, battery capacity and such. I would assume the engineer designing the system would look up the curves for the CB, and know how to collect the data to insure that it does not nuisance trip and still provides the level of protection required. Then again, using a simple handheld clamp maybe something an inspector would use to check equipment for compliance. I really don't know. It just seems like if you have some test equipment that has a feature like like that you require, it better be well defined and you should know what that definition is.

author: AllTheGearNoIdea
author_rank: Unknown
timestamp: December 07, 2018, 01:10:17 pm
content: Im very interrested in this post. I have had a lot of problems with LED warning lamps taking out very large MCB breakers, in industrail applications. Although I have quite a number of clamp meter never found one that provided a good indication of the real inrush. Im currrently using a current shunt and differential probe as an input to my scope. It was interresting to note that the measured inrush current was exactly the same as the predictive fault current of my building.This is for a bank of six led warning lamps that combined have a current less thean 0.2 of an amp at 230V

author: Fiveohfour
author_rank: Contributor
timestamp: December 08, 2018, 03:09:43 pm
content: Quote from: AllTheGearNoIdea on December 07, 2018, 01:10:17 pmThanks for the vote of support,i would be interested in knowing the meters you have with inrush, I have seen reports of inrush functions that were simply labeled as such and shouldn’t be. That said given your other equipment I assume you likely have some quality brand clamp metersSent from my iPhone using Tapatalk

author: Fiveohfour
author_rank: Contributor
timestamp: December 08, 2018, 03:10:36 pm
content: This is not the droid you’re looking for*waves hand*

author: Fiveohfour
author_rank: Contributor
timestamp: December 21, 2018, 12:45:07 pm
content: Seems I came to the wrong place for this question or it’s just too much of a pain and not worth the trouble for people to investigate Or the gpeople with the tools haven’t even read it lol. Understandable.I appreciate the input from Everyone who replied. Thanks for your time.Sent from my iPhone using Tapatalk

author: eKretz
author_rank: Frequent Contributor
timestamp: December 22, 2018, 09:06:54 am
content: I think it's just not something most consider a specific need. A goodmeter's min/max works just fine for most of the stuff I need to know. My Fluke 87V with an amp clamp at peak min/max has a sample spacing of 250 microseconds (¼ ms) - though this isn't RMS it's instantaneous. If I needed to get specific I'd use an oscilloscope so I could see the curve.

author: Gregg
author_rank: Super Contributor
timestamp: December 23, 2018, 03:46:29 am
content: Fiveohfour,I have an Amprobe ACDC-3000 that has a DC peak function with a claim of 1ms. I also have several DC clamp adapters that could be connected to my Fluke 289 or Hioki DT4282 or Siglent scopeI’m not sure what type of standard test setup you have in mind to ensure consistent and repeatable results for what you ask.• What current levels would be appropriate?• How would you determine actual current peak vs. meter reading and keep it calibrated during testing?• Resistive and/ or inductive loads separately and together?• Some AC superimposed on the DC to test if the clamp is only picking up DC?I suspect many forum members do not have the equipment to give definitive results that would be repeatable from different test setups.Maybe you should post some testing that you have done with a list of test equipment used and how the results vary. It may make for a more interesting discussion thread.

author: Fiveohfour
author_rank: Contributor
timestamp: January 31, 2019, 05:19:13 am
content: Quote from: Gregg on December 23, 2018, 03:46:29 amOh fun sorry for the late reply. I gave up after getting kind of bummed that a group of people with all these tools they’re known for tinkering can’t have their arms twisted into a little experiment.Having said that my knowledge level is so minimal I get that it just seems weird. The topic of inrush seems to not even be one many grasp/“believe in” or it becomes a “my meter with peak is just as good, Im sure of it because I feel it in my gut.Anyhow let me think about your questions for a moment. Does your fluke have the inrush function? I believe it does but don’t recall for certain. If so, the first would be devising best way to demonstrate peak vs inrush although I already linked how that works.As for others not having the equipment, at its most basic I was just hoping everyone with a inrush function equipped dc current clamp would test if the inrush function works in dc mode and what the behavior/results are. I know of only a few brands including fluke who do and that was my primary curiositySent from my iPhone using Tapatalk