Electronics > Beginners

AC Line Waveform Distortion

<< < (4/8) > >>

soldar:

--- Quote from: spiff72 on April 28, 2019, 04:32:30 pm --- I might have to repeat the experiment with all the lights in the house turned off and see if that makes a difference.
--- End quote ---
Probably not. You'd have to turn off a lot more than just lights and just your house. There are many electronic loads like that and they are all over the power grid. You might see a bit of difference but I doubt it. You would probably see the same shape even at the distribution transformer.

bdunham7:

--- Quote from: radiolistener on April 29, 2019, 02:19:47 am ---In my case, I connected mains to oscilloscope through toroidal transformer. Secondary coil is unloaded.
But when I load it with resistor, the waveform shape is the same, just a little smaller amplitude.

--- End quote ---

I'm guessing your 3rd harmonic is mostly coming from the toroid.  I know mains voltage freaks people out, but there's no reason you can't just poke your mains with the probes that are included with the Rigol as long as you set it for 10X and DON'T USE THE GROUND LEAD!  They're 300V CATII.  If you're nervous, just open up a device that has a polarized plug and uses a fairly small protection fuse, then probe downstream of the fuse. 

soldar:
Another really easy thing to do is to use a voltage divider. You can use 100K + 10K, connect the 10 K to neutral and the 100K to live and you divide the voltage but also have a current limiter so that even if you short the leads you are safe.

BravoV:
Never seen a perfect Sine wave shape from mains, mine is similar to OP too, using Fluke DP-120 HV Diff.Probe straight at mains that powered the scope it self.

Gyro:

--- Quote from: bdunham7 on April 29, 2019, 03:58:49 am ---I'm guessing your 3rd harmonic is mostly coming from the toroid.  I know mains voltage freaks people out, but there's no reason you can't just poke your mains with the probes that are included with the Rigol as long as you set it for 10X and DON'T USE THE GROUND LEAD!  They're 300V CATII.  If you're nervous, just open up a device that has a polarized plug and uses a fairly small protection fuse, then probe downstream of the fuse.

--- End quote ---


--- Quote from: soldar on April 29, 2019, 04:57:38 am ---Another really easy thing to do is to use a voltage divider. You can use 100K + 10K, connect the 10 K to neutral and the 100K to live and you divide the voltage but also have a current limiter so that even if you short the leads you are safe.

--- End quote ---

Guys, this is the Beginners section. We never suggest connecting scope probes to, or directly tapping the the mains, especially when the experience level of OP is unknown!  :palm:

Also, many Chinese scope probes are Cat I rated at 300V (even if they claim otherwise).

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod