Author Topic: Rigol 3058E DMM Offset between DCI Ranges  (Read 632 times)

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Offline IU8BBM

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Rigol 3058E DMM Offset between DCI Ranges
« on: January 28, 2017, 11:42:08 PM »
Hi guys,
while working at a curve tracer I've noticed an huge DCI Offset (200mA) while switching between 200m and 2A range of my Rigol DM3058E. Attached you'll find the IV char of a resistor.
The DMM always showed this problem, also immediately after buying it.



Is this a malfunctioning of the DMM or just a calibration problem? Anyone has previously noticed this issue on its own?

Thanks in advance for all the answers,
Luca

 

Offline 2N3055

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Re: Rigol 3058E DMM Offset between DCI Ranges
« Reply #1 on: January 29, 2017, 12:06:48 AM »
Curve before and after switching is linear, so it does look like a calibration problem.. in this case gain calibration because both curves start nicely from 0 so no offset...

So it it either that meter came with calibration problem, or that one of the shunts was damaged.. since error is large, you can use some other good working multimeter ( no need for high precision ) and see which of the ranges is the one with problem...

Anyways, repair AND/OR calibration is in order.

If it is in warranty, report it immediately...

Regards,

Sinisa
« Last Edit: January 29, 2017, 12:08:23 AM by 2N3055 »
 

Online TurboTom

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Re: Rigol 3058E DMM Offset between DCI Ranges
« Reply #2 on: January 29, 2017, 01:47:09 AM »
To me this looks very much like you didn't consider the burden voltage of your multimeter, i.e. you measured the test voltage across the resistor under test and the DMM's shunt resistor in series. That would actually be exactly the picture to expect when due to range switching of the multimeter, the shunt resistance changes. Try recording the voltage directly across the resistor that you're testing (if it's small compared to the voltmeter's input resistance). I guess there's nothing wrong with your DMM.

Cheers,
Thomas
 

Offline Wytnucls

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Re: Rigol 3058E DMM Offset between DCI Ranges
« Reply #3 on: January 29, 2017, 01:50:56 AM »
I think it's quite normal.
You didn't describe your set-up very well. Are you measuring the voltage across the resistor?
The value of the current shunt drops from 1.34 Ohms to 0.161 Ohm, as the meter switches to the higher 2A range.
Your test resistor has a value of 1.16 Ohm.
The step in your graph accounts nicely for the change in burden voltage.
 

Offline 2N3055

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Re: Rigol 3058E DMM Offset between DCI Ranges
« Reply #4 on: January 29, 2017, 02:15:38 AM »
I think it's quite normal.
You didn't describe your set-up very well. Are you measuring the voltage across the resistor?
The value of the current shunt drops from 1.34 Ohms to 0.161 Ohm, as the meter switches to the higher 2A range.
Your test resistor has a value of 1.16 Ohm.
The step in your graph accounts nicely for the change in burden voltage.

Ha, I thought he's measuring current that was ramping up with time.....
If OP is  measuring current  and voltage over a resistor and meter in series while ramping up voltage, you are correct...
I guess I should have asked to better explain it...
 


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