DC Current Probe with 5mA resolution from 0 0r 5mA to 300A range !! - Page 1
Forum section: electronics / testgear

author: kunaltg
author_rank: Newbie
timestamp: July 25, 2014, 04:51:46 am
content: Heyy Hello all !!I want A DC current Probe with follwing Specifications :-Range :- 0 or 5mA to 300AResolution :- Required is 5mA but 10 mA will also work.I have searched a lot on web ,,didn't found any .Please suggest if you know any probe with such specifications !!

author: BravoV
author_rank: Super Contributor
timestamp: July 25, 2014, 04:55:17 am
content: Budget ?

author: georges80
author_rank: Frequent Contributor
timestamp: July 25, 2014, 04:58:17 am
content: 5mA resolution when measuring 100's of amps???cheers,george.

author: BravoV
author_rank: Super Contributor
timestamp: July 25, 2014, 05:02:55 am
content: Quote from: georges80 on July 25, 2014, 04:58:17 amHence I was asking the budget, as old saying when it comes to measurement, a great dynamic range usually/always comes with "a price" too.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 25, 2014, 05:18:50 am
content: Quote from: BravoV on July 25, 2014, 05:02:55 aman old saying.you cant buy everything with money.good luck finding one.

author: kunaltg
author_rank: Newbie
timestamp: July 25, 2014, 05:20:58 am
content: Budget is not an issue ,, i just want to know whether Probe with such capabilities exists in this universe or not !!According to me its impossible, But i want to reconfirm it from experts like you!!

author: miguelvp
author_rank: Super Contributor
timestamp: July 25, 2014, 05:47:40 am
content: Half the Amp range but with accuracy "as low as" 5mA 20MHz probe.http://www.testpath.com/Items/Current-Probe-AC-DC-Clamp-on-20MHz-5mA--150A-TekVPI-Interface-117-414.htm15MHz version reconditioned (Requires TCPA300 Amplifier)http://www.testpath.com/Items/AC-DC-Current-Probe-15MHz-5mA--150A-RMS-Amplifier-Reqd--FINAL-SALE-NR-NC-117-790TS.htmnot reconditioned also requiring TCPA300 Amplifier:http://www.testpath.com/Items/AC-DC-Current-Probe-15MHz-5mA--150A-RMS-Amplifier-Reqd-117-790.htmSo the tech should give you 10mA on the range you are seeking but they just don't build them, maybe using a current divider?But I'm not expert by any means, just googled itEdit: lower range is not 5mA

author: AlfBaz
author_rank: Super Contributor
timestamp: July 25, 2014, 05:56:01 am
content: I'm unsure these probes will give the required 5-10mA resolution, especially when feeding an 8bit scope.If my calcs are anywhere near right we're looking at around 48db range which is like trying to hear someone whispering whilst standing next to a lawn mower

author: nctnico
author_rank: Super Contributor
timestamp: July 25, 2014, 07:02:42 am
content: Quote from: kunaltg on July 25, 2014, 04:51:46 amA shunt resistor:http://www.guildline.com/Datasheet/Guildline9211ADatasheet.pdfand any 8+ digit multimeter

author: Dave
author_rank: Super Contributor
timestamp: July 25, 2014, 07:43:05 am
content: Is it just me, or is his requested resolution not that difficult to achieve?300A at 5mA resolution means 60000 counts. A 5.5 digit multimeter connected to a high-current shunt would exceed that resolution. Accuracy would be rather poor, though, because at 300 amps things tend to get really hot, really fast. Unless you get some super low tempco shunt, your measurements are going to be all over the shop.But then again, he never mentioned what accuracy he's looking for...

author: Neilm
author_rank: Super Contributor
timestamp: July 25, 2014, 04:13:47 pm
content: The trouble with current shunts is ensuring that they are stable with the current - especially if it applied for long periods of time. The temperature drift will be much more than the 5mA. If we were to say 1mV / A that would be a current shunt of 1mohm. That would then have to dissipate 90W without drifting.

author: mzzj
author_rank: Super Contributor
timestamp: July 25, 2014, 08:03:00 pm
content: Quote from: Neilm on July 25, 2014, 04:13:47 pmThats more of a accuracy problem, not so much problem if OP only needs resolution.5mA accuracy at 300 Amps puts you in the "national metrology lab territory"IE. something like this in bigger version would do the trick:http://us.flukecal.com/products/electrical-calibration/electrical-standards/a40b-series-precision-current-shunts?quicktabs_product_details=2

author: mzzj
author_rank: Super Contributor
timestamp: July 25, 2014, 11:42:08 pm
content: Hit a jackpot when started to look for fluxgate/dcc-sersors:http://www.lem.com/hq/en/component/option,com_catalog/task,displayserie/serie,IT%2060-1000%20S/output_type,/This might look a bit more practical than squirrel-gage shunt.

author: alexwhittemore
author_rank: Frequent Contributor
timestamp: July 26, 2014, 01:50:55 am
content: Quote from: mzzj on July 25, 2014, 11:42:08 pmDammmmmmmmmmmmmn those are exotic.

author: Smokey
author_rank: Super Contributor
timestamp: July 26, 2014, 04:21:59 am
content: If you want RANGE + RESOLUTION + BANDWIDTH expect to pay a few thousand USD for it. I demo-d one of these. Totally sick if you need it.Check out the Tektronix probe amplifiers.http://www.tek.com/datasheet/current-probe/tcp300-tcp400-serieshttp://www.tek.com/sites/tek.com/files/media/media/resources/TCPA-Amplifiers-and-TCP300-400-Probes-7_4.pdf

author: Napalm2002
author_rank: Regular Contributor
timestamp: July 26, 2014, 04:49:13 am
content: Hioki

author: mzzj
author_rank: Super Contributor
timestamp: July 26, 2014, 07:44:20 am
content: That tek probe doesnt have resolution anywhere the resolution thread starter was asking for.LEM fluxgate sensors have incredible performance but the sensor is not exactly "clip on probe"

author: HighVoltage
author_rank: Super Contributor
timestamp: July 26, 2014, 08:41:59 am
content: I was also looking for a current probe at the low mA range and found two problems:1. They are really noisy2. They are really expensiveI ended up with a precision shunt resistor and a voltage probeThis was cheap and the signal was very stable.It is a real surprise to me, how expensive current probes are.

author: TiN
author_rank: Super Contributor
timestamp: July 26, 2014, 09:36:29 am
content: Tek TCP303 do not give you 5mA resolution when used on 50A range.I'm using one with amplifier from time to time, measurement look like this:TDS5034B + amplifier + TCP303A (black one).I will try some high current&resolution measurements later as well, already got twoLEM Ultrastab's.But they are by no means quick solution, as they need precision secondary measurements, low tempco burden resistor, and are not clip on either.

author: Rifter
author_rank: Contributor
timestamp: August 04, 2014, 06:18:31 am
content: Just thought I would update everyone and have decided to order the BM257. It shipped this morning from the eBay sellerThanks to all who contributed.I really liked the ut61e but it came down to counts not being everything, no back light, doesn't look as durable(will be used outdoors for automotive use) and having sub par input protection, while I don't intend to do any mains or high voltage work it's good to know my meter is properly protected just in case I ever need it.

author: alexwhittemore
author_rank: Frequent Contributor
timestamp: August 04, 2014, 06:20:56 am
content: Quote from: Rifter on August 04, 2014, 06:18:31 amI think you're in the wrong thread.