Is it possible to use oscilloscope in this case?

[Bondguy]

Is it possible to  check the voltage (of about 220V ) between   cathode and anode of a  thyristor with oscilloscope? I would use an isolation transformer  but what else must I be aware of?

[WackyGerman]

You better use a multimeter for that . It s more accurate and much easier

[Bondguy]

Oscilloscope is more useful because you can see all details (e.g. oscillating )

[WackyGerman]

Yes that s right . If you want to see the details it is more handy but you need additional equipment for safe measurements i.e. differential probe . In this case it would be the easiest way to use a scopemeter with floating inputs . You don t need to care about the earth potential in this case . But a scopemeter is not that cheap unfortunately

[Bondguy]

But if I use an issolation transformer I do not need to care about the earth potential either. Or am I wrong?

[WackyGerman]

Well if you do that then you have the problem that your oscilloscope will blow up because the voltage is too high . You say you have 220 Volt at the thyristor . That s the RMS value . So be careful , the inputs of your scope may be marked with 400 V or 200 V Peak max and that s the peak value .So that s U PP max =400 V .  Just calculate . U RMS x 1,4 = U Peak , 220 x 1,4 =308 V Peak , U PP = U Peak x 2 . So you would feed 616 V PP into your oscilloscope 

[Bondguy]

What is RMS value?Can you explain?
Can you explain a little more the calculation
 Just calculate . U RMS x 1,4 = U Peak , 220 x 1,4 =308 V Peak , U PP = U Peak x 2 . So you would feed 616 V PP into your oscilloscope
Thanks

[danadak]

If its a 2 channel scope then use it differentially, use the "Add" function, and the "invert"
selection on channel 2.

https://www.eevblog.com/forum/beginners/how-to-perform-differential-voltage-measurement-with-an-oscilloscope/

http://users.rowan.edu/~mease/resources/Fundamentals%20of%20Floating%20Measurements%20and%20Isolated%20Input%20Oscilloscopes.pdf


Regards, Dana.

[alsetalokin4017]

What if my scope's inputs are marked 300V RMS?  (For example DS1054z)

What if I use one, or a pair, of 10x attenuating probes?

What if I use one, or a pair, of 100x attenuating probes?

[janoc]

What if my scope's inputs are marked 300V RMS?  (For example DS1054z)

What if I use one, or a pair, of 10x attenuating probes?

What if I use one, or a pair, of 100x attenuating probes?

You should use a high voltage and, ideally, differential probe. Normal probes (even the 100x ones) are not designed to handle such voltages. E.g. the stock probes that come with DS1054Z are labeled 1x 100V or 10x 300V max. You finger slips, you move the switch on the probe while it is live and KABOOM.

[danadak]

Some specs -

http://datasheet.octopart.com/RP2200-Rigol-datasheet-26580153.pdf

https://en.wikipedia.org/wiki/Measurement_category


https://forum.tek.com/viewtopic.php?f=568&t=136026

http://support.fluke.com/find-sales/download/asset/1263690_6116_eng_h_w.pdf


Regards, Dana.

[vk6zgo]

Well if you do that then you have the problem that your oscilloscope will blow up because the voltage is too high . You say you have 220 Volt at the thyristor . That s the RMS value . So be careful , the inputs of your scope may be marked with 400 V or 200 V Peak max and that s the peak value .So that s U PP max =400 V .  Just calculate . U RMS x 1,4 = U Peak , 220 x 1,4 =308 V Peak , U PP = U Peak x 2 . So you would feed 616 V PP into your oscilloscope 

In an ac waveform,peak to peak voltages aren't real-----the positive & negative half cycles aren't present at the same time!
Peak voltage is as much as you get,which is 1.414 times RMS for a sinewave & some other waveforms.

P-p is really only to make it easy to measure voltages with an analog Oscilloscope (count the squares),or to determine the undistorted operating range of an amplifier stage,ADC,or similar.

[kao]

What if my scope's inputs are marked 300V RMS?  (For example DS1054z)

What if I use one, or a pair, of 10x attenuating probes?

What if I use one, or a pair, of 100x attenuating probes?

If the oscilloscope can measure up to 300 Vrms, 220 Vrms the measure can be However, you must comply with all safety precautions of manual. Usually it is an isolated power supply oscilloscope, for example, an isolation transformer or battery power, the right mode choice and divider probes.

Measurement 220Vrms mains via OWON XDS3102 oscilloscope with battery (see from 15:25, only russian language, sorry):