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Measure mains (230V) with osciloscope
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vk6zgo:

--- Quote from: mitrynicolae on November 18, 2018, 03:08:04 pm ---Hello everyone,

I have a simple yet complicated question (at least for me). How do I safely visualize with an oscilloscope the mains voltage? I have this scope https://www.linkinstruments.com/mso19.htm and the 1x/10x probe. Now there are multiple questions for which I still don't have a clear answer.
 - if the osciloscope with the 10x probe can only support 40v then this means that I need a 100x probe in order not broke the scope?
 - in the video #279 Dave Jones presented some ways in which beginner electronics hobbyists can blow up their scopes. Is there any setup, in which I could hook up the probe that could result in destruction of the scope or me being electrocuted?
 - can there be an issue if I put the ground lead to the live wire and the probe tip to the neutral?

To understand what I am trying to achive, I have this stabilizer: https://www.emag.ro/stabilizator-electronic-de-tensiune-electropower-ep-jjw-15kva-cp-jjw-15kva/pd/DW7WSYBBM/ and the producer claims that the stabilizer has a sinusoidal output. More over they claim that the output has 1% accuracy and a response time of 100ms. The issue is that when my home boiler (similar to this one http://www.ariston.com/uk/Wall-Hung_Boilers_Combi/clasnetone) starts up there is a huge voltage spike that eventually leads to an over voltage protection to shut down the mains in the entire home. If I gradually start the appliances in the house then there is no issue and the stabilizer work as it should, but if for some reason the mains was absent and then come back the spike in the stabilizer leads to shut down the mains to the entire home, As you can imagine the whole system enters in a loop from which is hard to recover and that could lead to some devices to blow up.

Thank you for your time!

--- End quote ---

Why do you need the stabiliser?

I have only seen them in TV & Radio Transmitters & Studios (huge ones in the latter).
They don't seem to be used at all in domestic situations in this country, & I have been to some remote places, where the Mains supply is pretty unstable.
(In one place, whenever they brought the big electrically operated  excavator up to the ore face at the mine, all the lights in town dipped! ;D)

On the other hand, if they are common in your country, maybe you should ask other users.
If they are happy, & only your one has this problem, I suggest you should  complain to the  manufacturer.
joeqsmith:
I'm not too surprised to hear about your problems with your line conditioner.   

Agree with others as far as possibly using a transformer.  I found one that has pretty good response that I tossed into a box and use to look at the AC line.   I wrote some software for my scope to use it to make some basic measurements but the transformer would be a bit limited for looking at transients. 

I don't do much at home with the AC line.  I did play around building a few differential probes.  Not something I would recommend for a beginner.   It may give you some idea how they work.   You could buy one fairly cheap with more than enough BW for what you are doing.  This one was fairly simple to build and was good for almost a MHz. 
https://youtu.be/_OZ5Xer84eo

I attempted to build something with a bit higher BW.  Somehow I don't think these would pass the IEC standards.
https://youtu.be/0thOfk4I3qs
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