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6487 - DC Ohm Measurement Configuration

2502, 6485, 6487 - Support
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Brian.Congdon
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6487 - DC Ohm Measurement Configuration

Post by Brian.Congdon » June 1st, 2015, 8:58 am

I am working on a project that uses the Keithley 6487 - to measure insulation and isolation resistances. The Electrical Insulation measurement must be a minimum of 102 Megohms and made 5-9 seconds after the initial application of the 50 VDC test voltage. The Electrical Isolation measurement must be a minimum of 51 Megohms and made 3-7 seconds after the initial application of the 50 VDC test voltage. I am using the LabVIEW KE6485.LLB and KE6485_32.dll to configure and use the -. Can you recommend a setup configuration that would be most effective in this situation?

Dale C
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Keithley Applications
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Re: 6487 - DC Ohm Measurement Configuration

Post by Dale C » June 1st, 2015, 12:35 pm

The Labview library for the 6487 is the same as the library for the 6485 and you are using it.
To have the 6487 source voltage and measure the resistance you need to.
1. Set up the voltage source. Use KE 6485 Configure Source DC VI
2. Apply the source for the set time you want. Use KE Control Source VI.
3. Take the current measurement and let the 6487 calculate the resistance. Use KI 6485 Configure Measurement VI.

That should do it.

Brian.Congdon
Posts: 8
Joined: May 29th, 2015, 7:11 am
Country: United States

Re: 6487 - DC Ohm Measurement Configuration

Post by Brian.Congdon » June 2nd, 2015, 1:41 pm

Thank you for your response Dale. I'm specifically interested in the Limit, Rate and Filters settings. The KE6485.LLB I'm using doesn't allow for direct modification of Rate and Filters, so I was planning on just writing the command string to the device using the KE6485 Write Instrument Data.VI. I am also planning on using the 25μA current limit, 6 power line cycles and the Median and Moving filters, but I would appreciate your advice on these settings.

Dale C
Keithley Applications
Keithley Applications
Posts: 2849
Joined: June 10th, 2010, 6:22 am
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Re: 6487 - DC Ohm Measurement Configuration

Post by Dale C » June 3rd, 2015, 6:04 am

The current limit setting is up to you. It all depends on what you need. So if you like 25ua, then great.
The NPLC setting of six is the sweet spot. It is probably the best setting for rejection of 60Hz noise. this is an integration rate of 100msec, I think it is a good idea.
The Median and moving filters are good ideas if you are having issues with noise.
What level of voltage, current and resistance are we dealing with here?
If the current measurement is below 1nA (1e-9A) then I would suggest to use the filters. But this level the guard and shield are more important.
The filters help out with noise, the guard and shield help the low current not be affected by stray resistance paths.

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