# Comparing current measurements of multimeters

#### Leonardo Camargo

Joined Oct 30, 2017
9
Have you guys ever watched Youtube multimeter reviews, in which they connect several multimeters in parallel, and measure the same voltage with all of them at the same time? The goal there is, having one of the meters considered as the reference/standard, to compare their measurements and calibration.
I would like to do something similar, but in my case, I would like to connect several multimeters in series and proceed to measure the same current, specifically in the microamp range, with all of them. I'd like to be able to go from a couple microamps to hundreds of microamps.

I have two questions:
1)Is this technically acceptable?
2)Is there a cheap way to do it?

#### Leonardo Camargo

Joined Oct 30, 2017
9
How were things setup?

Ron
The simplest way possible. I connected a 1 MOhm resistor in series with only my Fluke 289, and then connected both to my power supply. I stepped up the voltage from zero to 20V and got no reading on the Fluke. Same issue with the Fluke 87V. Now with the chinese brand meters, right out of the gate I got readings, they increased as I increased the voltage, as one would expect.

#### Leonardo Camargo

Joined Oct 30, 2017
9
I did a different setup this time. I connected my fluke in series with one of these electronic loads, and then connected both to 12v/10A power supply. Current goes through just fine, but no readings of either amps, miliamps or microamps from the Flukes (289 and 87V), but normal readings from the chinese brand meters.

I think indeed both of my Fluke meters are defective.

Joined Jan 15, 2015
6,698
The lowest current range on a Fluke 87 DMM for DC current is 60 mA with 0.01 mA resolution and an uncertainty of ± (0.4 % + 4). With 20 Volts applied and a 1 Meg Ohm load your current will be about 20 uA and you have 10 uA resolution so I would expect to see something in that last decimal place on the fluke. However, there is still the allowable four counts on the last digit. You are sure the Fluke is set for DC current? When I turn my 87V on it defaults to AC current and I need to hit the yellow button to switch to DC current. My older 87 (not a series V) defaults to DC current.

OK, just read your subsequent post but I think it would be strange you have two failed Fluke meters as that is a strange coincidence. No way the current fuses are blown is there? Not unusual to find blown fuses for the current inputs.

Measuring the input resistance on the 400 mA fused input it should be about 1 K Ohm and the 10 Amp input about 0.1 Ohm if even that high.

Ron

#### Leonardo Camargo

Joined Oct 30, 2017
9
You are sure the Fluke is set for DC current?

Ron
That was the problem, both Flukes were set to AC current. Damn I made a fool of myself now. Sorry everyone and much thanks for the inputs. Especially you Ron.

Thanks everyone.

Joined Jan 15, 2015
6,698
No problem, we have all been there and done that or at least something similar.

Ron

#### MisterBill2

Joined Jan 23, 2018
12,399
That was the problem, both Flukes were set to AC current. Damn I made a fool of myself now. Sorry everyone and much thanks for the inputs. Especially you Ron.

Thanks everyone.
Actually, we did get a worthwhile exercise in considering what the problem could be, so it was not all a waste. AND, besides that you did accept the advice and checked the setup and the settings. That is better than a whole lot of people who ask for hrlp and then ignore the advice. given.