| Electronics > Beginners |
| Oscilloscope for AC work ? |
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| joeqsmith:
If it were to just for a home outlet and a few small devices, a standard scope may be fine. Here is mine making some decent power measurements. https://youtu.be/04I7nHA_HxM |
| malagas_on_fire:
Another budget alternative is the uni-t 81b portable scope which is CATIII 600 but keep in mind it hasn't got isolation on the inputs jacks and some come with glass fuses :P http://www.uni-trend.com/html/product/General_Meters/Digital_Multimeters/UT81_Series/UT81B.html |
| Jwillis:
There is no danger measuring high voltage PROVIDED your at the SAME POTENTIAL as the line your measuring.This means you do not complete a circuit to ground or any of the other lines.This is why birds can sit on high voltage service lines .If you equipment is at the same potential as the line your measuring theirs no risk of damage.This is what isolation is for.Provided you don't exceed the maximum input voltage of the probe or the scope. The best and safest solution to measuring mains voltage is through a step down transformer and measure at low voltage.Any anomalies in mains will show up on the low side.then just do the math. Or better yet don't measure mains at all.Why? If you have to ask then you are not qualified to do so and need to get a service person that is qualified to do so.They have the training ,knowledge and equipment for the task. I simply don't understand why people ,when they get their first scope .need to run to the first outlet they see and stick the probes in.It's an AC sine wave .It's always going to be an AC sine wave no matter which country your in. |
| David Hess:
Either use high voltage differential probes with the oscilloscope of your choice or an oscilloscope with galvanically isolated inputs which is commonly designed specifically for power line measurements anyway. But do not combine these two options. |
| DDunfield:
--- Quote from: malagas_on_fire on May 04, 2019, 09:19:51 pm ---Another budget alternative is the uni-t 81b portable scope which is CATIII 600 but keep in mind it hasn't got isolation on the inputs jacks and some come with glass fuses :P --- End quote --- I have one of these, it's "OK" - UNI-T has been around for a while, and their stuff seems somewhat decent, but not up to the standards of the likes of Fluke or other top players. It's basically a DMM with graphical display ability - quite useful at times, but not what the OP is looking for. It has no math or real measurement capability. It doesn't have storage other than the trace on the screen, no zoom etc. In "scope" mode it functions like a fairly basic analog scope, except that the trace hangs around till the next trigger. The DMM leads are isolated/shrouded like most other DMM's. It's rated CAT II/1000 and CAT III/600 .. not sure I'd trust it like the Fluke, but I have no trouble poking around 120v NA mains with it. It is well built and insulated and there is no exposed metal. It has a BNC adapter which is insulated like the Fluke (but lower quality) not clear what if any ratings apply when the BNC adapter is used, unless you have a properly isolated probe it wouldn't apply anyway, I don't use the BNC around mains. It does come with an optical USB interface, and it's easy to make a optical RS-232 serial interface. I reverse engineered the protocol (which I documented somewhere) and wrote code to interface to it. It does let you save/recall the displayed waveform, so it would be possible to do some post-analysis on it, but it's just the display. There a review on it: https://www.eevblog.com/forum/reviews/review-uni-t-ut81b-scopemeter/ And a teardown of the UT-81C which is just a faster version of it: https://www.eevblog.com/forum/testgear/uni-t-ut81c-scopemeter-teardownreview/ Dave |
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