Tracking Mains waveform characteristics

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michael.farmer
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Tracking Mains waveform characteristics

Post by michael.farmer »

I am a retired RF engineer and infrequent user of my 2206B Picoscope. I would like to use this scope to monitor the amplitude and frequency variations in a generator-sourced mains supply. I would like to use the built-in scope functions to measure RMS amplitude and frequency, say, once per second and output the results to a spreadsheet file, either on my MacBook or some other data storage means (memory stick ?) via USB, and to do this over relatively long periods (1 -2 days). Can someone point me in the right direction please? Also what frequency resolution can I expect from this particular scope? I am running Picoscope 7 on a MacBook Pro. I realise that this is a bit like transporting coal in a Rolls Royce but make use of what you have !
PS I have set up my 2206B to measure 50Hz from the AWG. The time base is set to 100ms/div which gives a full trace every 1 second approx. I have selected RMS Amplitude and Frequency from Measurements and the values at the bottom of the display appear to update every second which is what I want, with a frequency resolution of 0.01 Hz. How do I export these two measurement values to a file as CSV data continuously?

Martyn
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Re: Tracking Mains waveform characteristics

Post by Martyn »

First you are going to need to be careful how you connect your scope up to the signal you wish to measure, you shouldn't be using the supplied x10 probes, but appropriate safety rated probes. Please see

https://www.picotech.com/accessories/ac ... gh-voltage

If you are using a recent version of the PicoScope 7 software it has a new feature which allows the measurements you record at the bottom of the screen to be exported to a CSV file each time they are calculated.
Measurement Logging.png
This is described in more detail in the relevant section of
https://www.picotech.com/library/oscill ... asurements

If you don't see this you will need to update your version of PicoScope 7
Martyn
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michael.farmer
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Re: Tracking Mains waveform characteristics

Post by michael.farmer »

Thank you Martin for your comprehensive response. I haven't had time to try it yet but feel sure it can solve my problem. I appreciate the mains warning, thank you. Having acted as a safety auditor in my working life I readily appreciate the dangers (and for what its worth, RF burns in my experience are worse than mains shocks; both can be lethal so I do take care.) I intend to make my measurements via a suitable isolated step down transformer. Thanks again.

michael.farmer
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Re: Tracking Mains waveform characteristics

Post by michael.farmer »

Hi Martyn, the logging facility behaves exactly as described but I still have one small problem. What I ultimately want to achieve is to produce a plot of frequency against time as I believe that a generator used to supply mains is occasionally dropping outside the normal accepted frequency limits. When I run the Picoscope logging facility I get a .csv file as expected but the date and time elements of this file are NOT comma separated and this gives me a problem when I import the file into the Numbers application on my MacBook running OSX Sonoma. The date and time appear as a single column and I have not been able to separate out the time element successfully. The following few lines, taken from my .csv file, show the problem.

Time (UTC +00:00 dd/MM/yyyy HH:mm:ss),RMS (A) (V),Frequency (A) (Hz)
21/03/2024 09:19:38,0.5639821,49.99844
21/03/2024 09:19:40,0.5639756,49.99792

Is there a simple solution for this? I have tried setting the data format for this column in Numbers to "space separated" (don't ask me how, I was just fiddling but it seemed to work!!!!) but this gives me a peculiar fault in that the seconds value increments beyond 59 as I progress down the table.

Thanks

river
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Re: Tracking Mains waveform characteristics

Post by river »

Is there a way to increase the frequency of the data logging rate? Nothing drastic, but perhaps between 1 and 10 Hz.

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