Masuring 50A DC - Page 1
Forum section: electronics / general

author: luudee
author_rank: Frequent Contributor
timestamp: September 27, 2023, 12:04:38 pm
content: Guys,are there any small hand held devices that will allow me to measure currents up to 50A DC ?Doesn't need to be very accurate +/- 0.5 A would be fine ...Thanks,rudiPS: Voltage range would be relatively low, around 12V would be good.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 27, 2023, 12:19:24 pm
content: +/- 0.5 A DC can easily be done with shunt resistor and a multimeterOr you use a current clamp meter, like this one:https://www.fluke.com/en/product/electrical-testing/clamp-meters/fluke-325

author: luudee
author_rank: Frequent Contributor
timestamp: September 27, 2023, 01:06:21 pm
content: Quote from: HighVoltage on September 27, 2023, 12:19:24 pmThank you HighVoltage !My Brain isn't working today, why didn't I think of a clamp meter ?!I thought about Shunt Resistor, etc, but at 50A I didn't want to deal with it, lol ...Best Regards,rudi

author: alm
author_rank: Super Contributor
timestamp: September 27, 2023, 02:26:21 pm
content: Since this is the metrology forum, for better accuracy than the common clamp meter look forDirect Current Comparator Transducerslike the LEM Ultrastab series.

author: mzzj
author_rank: Super Contributor
timestamp: September 27, 2023, 07:11:13 pm
content: Quote from: HighVoltage on September 27, 2023, 12:19:24 pmOP's wish for 0.5A/50A or 1% accuracy is bit too much for most of the clamp meters. Mentioned Fluke for example is specified for 2% and some pocket change of digits.There is some notable exeptions like Hioki CT6843A at 0.3% but this is close to 3000 usd kit

author: bdunham7
author_rank: Super Contributor
timestamp: September 27, 2023, 08:07:57 pm
content: You'll get better accuracy and much better zeroing for less money with a decent shunt. This one will read directly in mV, 1mV=1A.https://www.digikey.com/en/products/detail/riedon/RSA-100-100/4967078

author: alm
author_rank: Super Contributor
timestamp: September 27, 2023, 09:14:40 pm
content: Quote from: bdunham7 on September 27, 2023, 08:07:57 pmBetter than a Hall effect clamp meter, yes. Better than DCCT, unlikely. If you're not careful, thermal EMF could already eat into that uncertainty budget of 500 uV given the shunt is likely to get warm. But then neither a DCCT nor a shunt that can get hot are a truly convenient handheld device like a clamp meter, though they could both certainly be made portable.

author: bdunham7
author_rank: Super Contributor
timestamp: September 27, 2023, 09:36:01 pm
content: Quote from: alm on September 27, 2023, 09:14:40 pmI was only comparing to the clamp meter. The shunt is cheap and simple, which is what I expect the OP wants. If that 1% spec is necessary, Riedon makes these with a 0.1% nominal tolerance (at 25C) and 0.02% tempco from 15 to 80C. At 50A, the 1mR 100A-rated shunt will be dissipating 2.5W, so perhaps a small fan to keep it under 80C?https://riedon.com/media/pdf/RS.pdf

author: CosteC
author_rank: Regular Contributor
timestamp: September 29, 2023, 12:16:38 pm
content: Quote from: HighVoltage on September 27, 2023, 12:19:24 pmUnfortunately this is incorrect. FLUKE 325 is not accurate enough. It offers 2% +5 LSB, at 400 A range (40 A range is too small) it means +/- 1.5 A while desired accuracy of 0.5 A at 50 A is +/- 1%.EDIT: APPA MA3/MA5 136/138 can provide +/- 0.95 A error, but this is more or less as far as you can go with hall sensor and reasonable price.None of "ordinary" clamp meters can provide such accuracy as are based on Hall sensors. There are different types, yet far more expensive.

author: beanflying
author_rank: Super Contributor
timestamp: September 29, 2023, 12:50:30 pm
content: The UNI-T 210E is actually very good at higher currents when tested against known a set of 0.25% Murata shunts I own. The key to using it is to zero it before each reading and don't move it around as the sensor can tend to pick up errors (applies to most of this type).Shunts like these are 'affordable' toohttps://au.element14.com/murata-power-solutions/3020-01103-0/shunt/dp/1498416?CMP=i-55c5-00001621and come is a heap of ranges. I went with 0.1V 10A, 0.1V 100A and the 500A one is 50mA. Parly so these can be close to direct reading from a meter without doing any math.The other option which might suit is look at the R/C test gear there is a bunch of this sort of thing around some trash and some out of the USA brands much better. This one I have used a bit and is great for quick and dirty measurementshttps://hobbyking.com/en_us/turnigy-180a-watt-meter-and-power-analyzer.html

author: mendip_discovery
author_rank: Super Contributor
timestamp: September 29, 2023, 01:09:54 pm
content: Quote from: CosteC on September 29, 2023, 12:16:38 pmThis is the last 9 Fluke 325 meters to bless my bench.

author: luudee
author_rank: Frequent Contributor
timestamp: September 29, 2023, 01:12:24 pm
content: Guys,I have to apologize, I did not mean +/- 0.5A as a hard target. I didn't think about it in absolute terms.2% will be just fine. I already placed an order the Fluke 325 ... This is not so much for my Lab, butfor my house ...Many Thanks for all the suggestions !rudi

author: HighVoltage
author_rank: Super Contributor
timestamp: September 29, 2023, 01:36:40 pm
content: I had several Fluke 325 over the years and each one was much better than the stated 2%

author: alm
author_rank: Super Contributor
timestamp: September 29, 2023, 01:50:14 pm
content: It depends what you're trying to do. If it needs to be a traceable measurement, then you either rely on the manufacturer specifications or you have to collect the data to characterize the device yourself, which can be a lot of work. So often the simplest is to buy something that has the guaranteed specifications from the manufacturer that you need, and not "usually will be good enough if the weather is not too cold".Obviously it it's for a simple measurement at home none of this matters, but then why post this in the metrology section

author: mendip_discovery
author_rank: Super Contributor
timestamp: September 29, 2023, 01:56:22 pm
content: Quote from: alm on September 29, 2023, 01:50:14 pmBecause that lot over in the test gear section are crazy with a capital Z. You wouldn't get a simple answer out of them. The TEAS is rather strong with them.

author: CosteC
author_rank: Regular Contributor
timestamp: September 29, 2023, 02:41:59 pm
content: Quote from: HighVoltage on September 29, 2023, 01:36:40 pmLove this almost religious faith in FLUKE. Especially faith in 'shyness' of huge corporation to specify so high real accuracy.Reality is under good conditions any sensible meter is more accurate than specification. Yet outside of room temperature, with noise and distortion present accuracy is dropping.Under comfortable 23'C, well centred conductor, no stray magnetic fields any meter will be more accurate than specs. The difference is FLUKE will meet its specs in field. UNI-T - not nesesery.Unit will drift more than APPA, and APPA probably more than FLUKE (probably as at least one FLUKE is APPA)

author: luudee
author_rank: Frequent Contributor
timestamp: September 29, 2023, 02:56:56 pm
content: Quote from: CosteC on September 29, 2023, 02:41:59 pmFluke makes some really nice equipment. I'd say more than just home use. I get myFluke 289 calibrated, and it is quite reliable and accurate.Sure, it does not compare to my SDG3065 or soon to arrive Keithley DMM6500 ...But none of those are hand held, and neither one can measure DCA of 50A (and more).Yes, I saw all the comments about shunt resistors, and I fully understand that I couldmake myself a small box ... etc etc etc.That is not the path I wanted to pursue for this particular requirement. A clampmeter is perfect for what I need it, and 2% is plenty !!!I truly appreciate all the comments ! Many many thanks everybody !!!rudi

author: mendip_discovery
author_rank: Super Contributor
timestamp: September 29, 2023, 03:05:18 pm
content: Quote from: CosteC on September 29, 2023, 02:41:59 pmI am a bit of a brand snob, I like to have good stuff if I can afford it but I am not faithful to Fluke just because it's "Made in America". I find that if you buy a Mitutoyo vernier calliper there is a <1 in 100 chance of it being rubbish, on the other hand, a cheap no no-brand thing and you will be lucky to get >1 in 100 which is any good. I like to have confidence that the kit I use will give me a realistic and repeatable result and live up the the safety specs it claims.The Fluke 325s I posted about were all in the lab at 22 ish degrees. Though I have quite a few that I have done onsite in uncontrolled environments but still will with a decent 10 or 50 turn coil. The biggest issue is its very hard to get the measurement uncertainty lower with the coils as any current error gets magnified by the number of turns.

author: mawyatt
author_rank: Super Contributor
timestamp: September 29, 2023, 03:20:33 pm
content: There are some things that we place considerable trust in, like Volts, Ohms and Current. This is why we have 3 KS34465A, DMM6500 an HP34401A and AG34401A. Our "goto" handheld DMM is an original Fluke 87 from way back when they were originally introduced, is still spot on for all measurements!!IMO Fluke is the ultimate professional handheld DMM, nothing comes close when long term reliability and accurate repeatable measurements over many decades are consideredBest,

author: luudee
author_rank: Frequent Contributor
timestamp: September 29, 2023, 04:01:00 pm
content: Quote from: mawyatt on September 29, 2023, 03:20:33 pmI agree with Mike !!! They are reliable ! Don't believe meCheck this out:I just pulled out this Fluke 23 from Storage. I had it for roughly 35 years. Thelast 10++ years it was in storage, until now.It even powered up, I thought for sure the battery leaked all over the unit bynow, still have to open and inspect. The LCD appears to be dying, it has alarge oval black spot, but it disappears when I power it on ...Cheers,rudi

author: mzzj
author_rank: Super Contributor
timestamp: September 30, 2023, 05:55:00 am
content: Quote from: CosteC on September 29, 2023, 02:41:59 pmHA!Try that with the tc-K temperature measurement part of Fluke current clamps.Sure it is more of extra features but it is a truly miserable piece of shit if you try to do full calibration including the thermocouple measurement input.TcK input in most Fluke current clamps drifts all over the place and is within the specification limits twice per day.

author: laichh
author_rank: Regular Contributor
timestamp: October 02, 2023, 07:52:47 am
content: How about the TI INA254 Evaluation board?https://www.ti.com/tool/INA254EVMAccording to the datasheet, the system gain error is ±0.05% typical or ±0.5% max. The total shunt + amplifier TC of ±45 ppm/°C max is as good as you can get on a Bulk-Metal Foil shunt for its size.