Products > Test Equipment

[SOLVED]HP/AGILENT/KEYSIGHT 34401A 2W Ohm Problem

<< < (7/11) > >>

coldframe:

--- Quote from: robrenz on February 18, 2014, 02:15:07 pm ---Temperature Coefficient.  In this case I implied TCR for Temperature Coefficient of resistance which is ppm change in resistance per degree change of resistor temperature.

--- End quote ---

Oh.. I see
Thank you for the explanation
So, This resistor measures a stable ohms on a known good meter.
* Temperature Coefficient (ppm/°C) ±5

Dr. Frank:

--- Quote from: coldframe on February 17, 2014, 06:18:31 pm ---a problem comes up

Hi,

It's all fine, except it's got a fault when measuring ohm with 2-wires again

For example.
I will get readings from 9.5 Ohms Value when Power On
But, Over time, Increase Ohm Value 10.7 Ohm
See attached.

*  When using 4-wires-measurement everything's alright.

Did anyone have that problem before?
Thank you

Coldframe

--- End quote ---

Don't understand your new problem, sorry. And my instrument is now rock stable in Ohm again, right from the beginning.


Zero Ohm reading is now ok, in 2W Ohm, in the beginning, and a short also reads << 1Ohm after warm-up / later?

Then you measure a 9..10 Ohm resistor, which reads always the same over time, when you use 4W Ohm?

And only if you measure the same resistor in 2W mode, then the reading will go up over time?

What kind of resistor do you measure?

Frank

robrenz:
Here is a thought,  In 2 wire mode even if you zero out the lead resistance you are seeing the TCR of the resistor and the copper leads. Also since the connection points are carrying current and measuring voltage drop there will probably be a greater thermal emf generated. Reversing the connection and seeing the difference in readings will give a clue as to how much thermal emf is involved.

I am not saying that there isn't something wrong with the meter but you have to consider the above points.

coldframe:

--- Quote from: Dr. Frank on February 18, 2014, 03:19:56 pm ---Don't understand your new problem, sorry. And my instrument is now rock stable in Ohm again, right from the beginning.


Zero Ohm reading is now ok, in 2W Ohm, in the beginning, and a short also reads << 1Ohm after warm-up / later?

Then you measure a 9..10 Ohm resistor, which reads always the same over time, when you use 4W Ohm?

And only if you measure the same resistor in 2W mode, then the reading will go up over time?

What kind of resistor do you measure?

Frank

--- End quote ---

Hi, Dr. Frank

Yes, When using 4-wires-measurement everything's alright.
Have you seen the Attatched Picture?
Only 2-Wires Over time, continuous increase

This is Resistor Specification.
http://www.te.com/catalog/pn/en/1624323-4

Do you have any good ideas?

Thank you
coldframe

coldframe:

--- Quote from: robrenz on February 18, 2014, 03:42:19 pm ---Here is a thought,  In 2 wire mode even if you zero out the lead resistance you are seeing the TCR of the resistor and the copper leads. Also since the connection points are carrying current and measuring voltage drop there will probably be a greater thermal emf generated. Reversing the connection and seeing the difference in readings will give a clue as to how much thermal emf is involved.

I am not saying that there isn't something wrong with the meter but you have to consider the above points.

--- End quote ---

Please understand,  I'm Not native English speaker

2-Wire
Attachment #1 Small Resistor Box
Attachment #2 Start
Attachment #3 10 Minute Later

4-Wire
Attachment #4 Stable

even now, on the increase....
what seems to be the trouble?   

Thanx

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod