How to connect HV probe to NI-DAQ?

[shreeyansh]

I have a Tektronix P6015A HV probe (1000X) to measure voltages in the range of 7 kV to 20 kV. Currently, I have connected it to an MSO-X 2024A oscilloscope to monitor the values. I want to connect the probe to a NI-DAQ device to read those signals and monitor it using LabView.

[RTSLVU]

Well the physical connection is the same as for an oscilloscope, although you may need the proper adaptor for your DAQ device to accept a BNC connection.

In general you are just measuring a scaled voltage, so just like setting the input attenuation on an oscilloscope, you will need to use the scaling factor (1000x) in your LabVIEW program. 

There are several ways to do this. You can set up scaling in NI-Max for DAQ-Mx. I suggest you also read the DAQ-Mx help. Or you can just read the scaled voltage directly and scale it (multiply measurements by 1000) in your program.

[JÞB]

WARNING: That probe has a single-ended 0-20V output!  It IS capable of damaging your DAQmx device with inputs greater than 10kV!  I do not recommend this configuration for transfer to any internal or external client user!  They will.be unhappy with the result of your engineering mistake.  You could clamp the probe output to 10V.

Also, you will need to adjust the compensation using the MSO scope. There will not be an easy means to do that on your DAQmx device.

[RTSLVU]

@JÞB wrote:

WARNING: That probe has a single-ended 0-20V output!  It IS capable of damaging your DAQmx device with inputs greater than 10kV!  I do not recommend this configuration for transfer to any internal or external client user!  They will.be unhappy with the result of your engineering mistake.  You could clamp the probe output to 10V.

Also, you will need to adjust the compensation using the MSO scope. There will not be an easy means to do that on your DAQmx device.

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@JÞB makes some good points.

It might be easier and safer for you to download the Agilent Technologies / Keysight Technologies MSO-X 2024A LabVIEW drivers and use the scope itself as the DAQ. I haven't looked at these exact drivers but most will allow you to get the waveform data from the scope and use it in LabVIEW.

[rolfk]

Aside from all the other remarks, there is also a possible safety risk, including damaging your DAQ and/or computer seriously if something goes wrong, and even potentially cause a health hazard. 10kV is serious voltage!

That probe is NOT isolated, so if the ground reference of your measured signal is not exactly on the same ground as your computer equipment, or the wiring is not 100% correct, or there is some wire damage anywhere, you may end up having your devices float on some high voltage and touching your computer or anything else could be actually deadly.

[Kyle97330]

Even if you do connect it, possibly requiring an adapter of some kind, the probe in question is expecting to be connected to a Tek scope with an impedance of 1 MΩ.  There are dozens of DAQs but I picked one at random and it's listed as having analog input to ground impedance of 10 GΩ when on and 1,200 Ω when off.  I don't know exactly what would happen if you connected it, but I suspect that you wouldn't get the values you wanted and might damage something.

[JÞB]

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@Kyle97330 wrote:

Even if you do connect it, possibly requiring an adapter of some kind, the probe in question is expecting to be connected to a Tek scope with an impedance of 1 MΩ.  There are dozens of DAQs but I picked one at random and it's listed as having analog input to ground impedance of 10 GΩ when on and 1,200 Ω when off.  I don't know exactly what would happen if you connected it, but I suspect that you wouldn't get the values you wanted and might damage something.

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Not much of an issue, it might throw off any probe compensation so, rise / fall time and overshoot / undershoot measurements would be the only concern.   

Addressing rolf's concern; the common reference issues would still exist using that probe on an MSO!  10kV is dangerous anywhere!  If you are not specifically trained in making or designing HV measurements, call an expert!  I simply assumed that the OP WAS qualified to work at High Voltage. 

[rolfk]

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@JÞB wrote: Addressing rolf's concern; the common reference issues would still exist using that probe on an MSO!  10kV is dangerous anywhere!  If you are not specifically trained in making or designing HV measurements, call an expert!  I simply assumed that the OP WAS qualified to work at High Voltage. 

You would be surprised what I have seen in real world (or maybe not).

At one point there was this HV measurement setup (“only” 4 kV but common mode of 2 kV) connected to an oscilloscope. To avoid the scope being fried instantly it was powered through an isolation transformer. As you could not touch the front panel and even the plastic knobs were to dangerous it was connected through a glass fiber isolated serial interface to a computer to remote control it. I was getting the jibes just seeing that but they were happily doing regular measurements that way. 

[JÞB]

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@rolfk wrote:

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@JÞB wrote: Addressing rolf's concern; the common reference issues would still exist using that probe on an MSO!  10kV is dangerous anywhere!  If you are not specifically trained in making or designing HV measurements, call an expert!  I simply assumed that the OP WAS qualified to work at High Voltage. 

You would be surprised what I have seen in real world (or maybe not).

At one point there was this HV measurement setup (“only” 4 kV but common mode of 2 kV) connected to an oscilloscope. To avoid the scope being fried instantly it was powered through an isolation transformer. As you could not touch the front panel and even the plastic knobs were to dangerous it was connected through a glass fiber isolated serial interface to a computer to remote control it. I was getting the jibes just seeing that but they were happily doing regular measurements that way. 

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And no, I would not be surprised. But then, I AM am expert with HV measurement design and practices. 

[xwang0329]

Naively, I hooked up my Tekctronix probe (1300V max, 500X attenuation)  to a daq USB-6009. Here is how it measured out. It ironically works for positive voltage. But for negative voltage, the DC voltage behaves like square pulse. Idk why.