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Measuring 220V AC with 2204

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Measuring 220V AC with 2204

Postby adynis » Sun May 17, 2009 1:07 am

I have a 1-10x probe. The 220AC has a amplitude of 320V ... so with 10x probe the limit would be 32V... The protection limit of the 2204 is +/-100V ... so I could measure directcly the voltage of the power network ?
If my calculation are correct... what would happend if, accidentaly, I change the probe from 10x to 1x ... while conected to 220V AC ? The internal protection can support, or I damage definitivly the oscilloscope ?

Thank you.

PS. sorry for my english.
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Postby Robin » Mon May 18, 2009 9:07 am


If you want to measure mains voltages, you must use differentail probes that are rated and designed for this purpose:

http://accessories.picotech.com/active- ... robes.html

These probes permit the measurement of signals which are not referenced to earth using a conventional earthed oscilloscope. This enables mains voltages to be tested.

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Postby pmgant » Mon Jun 08, 2009 8:24 pm

Sorry for shouting in the title bar but we're talking about life and limb here. Both the scope and your computer will react very badly if subjected to mains voltages, even through a 10:1 probe. Amongst the problems are:

1) What is the breakdown voltage of your 10:1 probe and are you sure that it can stand 320 volts?

2) If you connect the tip of the probe to the hot side then where do you connect your scope ground? Neutral may not be at ground potential and the mains ground MIGHT be a safer option but I wouldn't like to bet my life on it. In any event connecting a 10:1 probe between live and ground may trip the breaker because the device might think that there's a ground fault.

3) The electrical noise will be horrible and you will not get a valid result.

4) One mistake and you're gone.

Please, walk away from this idea and live to fight another day.

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