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| A look at the Uni-T UT210E |
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| Kean:
As --- Quote from: ThunderZed on October 22, 2021, 01:23:45 pm ---so we can answer the question: can this clamp measure down to 8-10mA in those domestic conditions with enough reliability? --- End quote --- As shown by the results of radiolistener's tests the readout of the UT210E at low AC currents is pretty ordinary (i.e. useless). If you want to properly measure AC leakage currents then the UT251A Precision Leakage Clamp Meter is a much better option, as it has 1uA resolution on the lowest range. It is pretty much only usable for low frequency AC leakage measurements though. Another option which I quite like is the SE-07 AC/DC Clamp Meter which has a 0.1mA resolution on its 400mA scale, and I've confirmed this can measure 1mA at 50Hz reasonably accurately. It is available on AliExpress, and I've had one for many years and prefer it to my UT210E's. Attached are some comparison measurements I just took using a test jig I made for testing RF current probes. I measured the output voltage of the PSG9080 output (50Hz sine) with a Keithley 34465A, and measured the current at each setting with two different UT210E's, a UT251A, and a SE-07. (I just noticed the third spreadsheet column is labelled "Irms (mA)" but is actually in amps. :clap:) The fact you are measuring leakage currents at 220-230V AC (vs our small voltages) doesn't change the way the current meters work. Also note that radiolistener did his calculations based on his measured 50 ohm load, but for my measurerments the current will actually be the PSG9080 output voltage into 100 ohms (50 ohm generator output impedance plus 50 ohm load) and the 34465A measurement was just a sanity check. I then doubled that measurement to simplify comparison. The PSG9080 only allows the output set in Vpp, which is why I have that column in the spreadsheet. My load resistor measured about 50.8 ohm DC, and the PSG9080 output measured about 49.6 ohm when off, but the numbers are just meant as a ballpark to show why the UT210E is not suitable. Forgot to mention: I checked at what point my two UT210E's switch from reading 0mA to 1mA, and it was at 1.58Vp and 1.48Vpp, so 790mV RMS (7.9mA) and 740mV RMS (7.4mA) 523mV RMS (5.2mA) and 559mV RMS (5.6mA). |
| radiolistener:
--- Quote from: ThunderZed on October 22, 2021, 01:23:45 pm ---we know the conditions: 50-60Hz, 220-230V AC (here in Italy) and a 1.5mm (= 0,059 in) diameter ground wire "many" meters (don't know) long. So could you please test this clamp on 2A scale in these conditions and tell me what's its minimum and "reliable enough" detectable AC value? --- End quote --- Voltage doesn't matter here, because UT210E measure current. The results for 220V mains will be exactly the same as shown on my measurement results. --- Quote from: ThunderZed on October 22, 2021, 01:23:45 pm ---I mean it'd be fantastic if you could compare its minimum value with a more reliable tool (eg. fluke) --- End quote --- BM867S pefromance is the same as Fluke, this is very precise and reliable DMM. It has 0.03% for DC and 0.3% for AC RMS. --- Quote from: Kean on October 22, 2021, 03:12:27 pm ---The PSG9080 only allows the output set in Vpp --- End quote --- The voltage on my measurement is RMS voltage measured with DMM (BM867S). This is not what on PSG9080 display. I just tune PSG9080 output to get required voltage on a dummy load by checking it with DMM and didn't bother what voltage is shown on PSG9080 display :) It is possible that resistance of dummy load was a little bit higher during my experiment, because it was connected through alligator clips. It may add a little resistance. I was used low resistance probes to measure dummy load, so 49.85 Ω don't include alligator clips resistance. Also, different UT210E may have a little bit different results, because they have different calibration. |
| ThunderZed:
Ok, I know I can't go on my personal "domestic" trouble here because it'd be OT, I just wanted to know from you if I could consider this "famous" tool for my goal but the answer is no if I'm not wrong despite I don't need "so much accuracy" (see my personal thread if you wish):-+ |
| radiolistener:
I don't see why no. It is very useful for testing or research mains distribution box. And it detects current down to 5-7 mA. Also it is very useful for testing DC current consumption, especially if you're needs to measure more than 10 Amps. |
| ThunderZed:
Sorry, I've misunderstood this --- Quote from: Kean on October 22, 2021, 03:12:27 pm ---As shown by the results of radiolistener's tests the readout of the UT210E at low AC currents is pretty ordinary (i.e. useless) --- End quote --- I've heard quite different opinions about this ut210e: someone says it's able to measure down to 10mA, someone else says it's not. Look at the pic in my attachment taken from another forum and posted by a final ut210e user. The forumers say: 1) this clamp is not reliable enough measuring only one lead on 2A scale; 2) if looping the wire 10 times this clamp measures 20 times the real value. Consider that I asked them if this clamp will be good enough for my specific goal in my scenario. Maybe that user/forumer/buyer was just unlucky and got a "defective" ut210e? |
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