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I bought a handheld o-scope. It says Maximum input: 10X: 600 Working Voltage. Does that means I can hook it up to 240V line voltage to see if I am getting dirty electricity?
newbie wants help with o-scope
- Thread starter Volttrekkie
- Start date
Yes and no.
If you have an oscilloscope probe set to 10X, this will allow you to connect to 10 times the maximum input voltage of your oscilloscope.
By definition, a "handheld oscilloscope" will be floating. It has no connection to ground. This then becomes a safety issue. If you don't know what you are doing you can blow your scope, or worse, you can electrocute yourself.
All line voltages I have observed look dirty. You never get a clean looking sine wave from mains supply.
As per reply, it can get VERY dangerous !! The DSO "Earth" will be either Neutral or LIVE !! depending on house wiring. You can use an isolation
transformer, even better, with say10:1 reduction - or make up a PURE resistance divider, again with 10:1 ratio.
If you want to check current, there are plenty of pick up coils for that. There are other tricks as well.
What is the make / model of the DSO?
transformer, even better, with say10:1 reduction - or make up a PURE resistance divider, again with 10:1 ratio.
If you want to check current, there are plenty of pick up coils for that. There are other tricks as well.
What is the make / model of the DSO?
Read these before you go looking at libne voltages -
https://www.tek.com/document/techni...lloscope-measurements-and-operator-protection
https://www.keysight.com/upload/cmc_upload/All/Probing-6-Hints-Scopes-Dec12-2007-webcast.pdf
And are the probes rated for 600V ?
Regards, Dana.
https://www.tek.com/document/techni...lloscope-measurements-and-operator-protection
https://www.keysight.com/upload/cmc_upload/All/Probing-6-Hints-Scopes-Dec12-2007-webcast.pdf
And are the probes rated for 600V ?
Regards, Dana.
As others have said:
- The handheld oscilloscope will be at the mercy of what voltage is applied to its negative terminal. In other words, if you have a typical probe with an alligator clip and a tip and tie the alligator clip to the live wire, the oscilloscope will be elevated to that potential (240Vrms). If you tie the alligator clip to the neutral wire, the same thing happens. Since the neutral wire may have an elevated potential in relationship with the ground (or your hand), both scenarios have the risk of shocking you. That is why it is usually recommended to either reduce the voltage level that will be connected to your oscilloscope.
- The input specification of the handheld oscilloscope seems to consider that you are using a probe that has a built-in circuit that divides the voltage in its terminals by a factor of 10 (also called 10x probe or 10:1 probe). The oscilloscope then seems to handle up to 60V on its input (600V / 10). However, you must consider two other factors:
- The probe itself must be able to handle all this voltage.In your case, the probe must be able to handle up to 240Vrms or 339V of peak voltage (the maximum amplitude or a 240Vrms sinewave). To make things safer and account for normal variations on the electrical supply, give it some margin: perhaps 300Vrms (424Vpeak) are probably ok.
- The probe itself must be safe enough to handle the power that can be made available from a common household outlet in case something goes wrong. In industry, this is usually specified by its CAT ratings. For a common household outlet, you need the probe to be CAT II rated.
http://www.ni.com/white-paper/5019/en/
- If your handheld oscilloscope has two or more inputs or other exposed metal, be very cautious while making the measurements as the other metal parts may be energized.
Regarding seeing the voltage as "dirty": as mentioned before, the outlet rarely has a pure and clean sinewave as motors, switching power supplies, CFL lightbulbs and other highly non-linear loads introduce a number of interferences (harmonics) to the lines.
- The handheld oscilloscope will be at the mercy of what voltage is applied to its negative terminal. In other words, if you have a typical probe with an alligator clip and a tip and tie the alligator clip to the live wire, the oscilloscope will be elevated to that potential (240Vrms). If you tie the alligator clip to the neutral wire, the same thing happens. Since the neutral wire may have an elevated potential in relationship with the ground (or your hand), both scenarios have the risk of shocking you. That is why it is usually recommended to either reduce the voltage level that will be connected to your oscilloscope.
- The input specification of the handheld oscilloscope seems to consider that you are using a probe that has a built-in circuit that divides the voltage in its terminals by a factor of 10 (also called 10x probe or 10:1 probe). The oscilloscope then seems to handle up to 60V on its input (600V / 10). However, you must consider two other factors:
- The probe itself must be able to handle all this voltage.In your case, the probe must be able to handle up to 240Vrms or 339V of peak voltage (the maximum amplitude or a 240Vrms sinewave). To make things safer and account for normal variations on the electrical supply, give it some margin: perhaps 300Vrms (424Vpeak) are probably ok.
- The probe itself must be safe enough to handle the power that can be made available from a common household outlet in case something goes wrong. In industry, this is usually specified by its CAT ratings. For a common household outlet, you need the probe to be CAT II rated.
http://www.ni.com/white-paper/5019/en/
- If your handheld oscilloscope has two or more inputs or other exposed metal, be very cautious while making the measurements as the other metal parts may be energized.
Regarding seeing the voltage as "dirty": as mentioned before, the outlet rarely has a pure and clean sinewave as motors, switching power supplies, CFL lightbulbs and other highly non-linear loads introduce a number of interferences (harmonics) to the lines.
PLUS .. if you have grid tied solar panels, or any neigbour (every 3rd), then that can add sheetloads of noise !
I wasn't aware of the uncleanliness of solar panel inverters. Thanks!PLUS .. if you have grid tied solar panels, or any neigbour (every 3rd), then that can add sheetloads of noise !
It is the Jinhan JDS2022A. The input resistance is 1Mohm/10Mohm +/-2%. Does that say anything?
So, I guess since it is a handheld, I can become ground and fry?
Oscilloscope's input impedance is usually 1MΩ. This changes to 10MΩ with a 10X attenuation probe. Your scope max input is 40V, or 400V with 10X probe.
It would be advisable to connect the probes via an isolated step-down transformer, for example, 240VAC to 12VAC transformer. This will give you the isolation protection as well as reduced voltages
It would be advisable to connect the probes via an isolated step-down transformer, for example, 240VAC to 12VAC transformer. This will give you the isolation protection as well as reduced voltages
Oh, OK. Well, it is no big deal to wire up a 40VA transformer and step it down from 240V to 24V. I have fried many of them. But I don't get why I can probe 240V with my multimeter but can't with the oscilloscope.
It is a matter of safety.
When you use your multimeter, you generally will be holding the insulated body of the probes and not the metal tips of the probes themselves.
When you use the oscilloscope, you have to clip the grounding clip on to the AC mains wiring. At some point you might come into contact with high voltage and this could prove to be lethal.
Take this advice seriously. Don't even think of doing it.
