Author Topic: Portable oscilloscope probes for measuring mains  (Read 656 times)

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Offline FlukenewbieTopic starter

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Portable oscilloscope probes for measuring mains
« on: April 14, 2022, 08:37:02 pm »
I just recently got my first scope, an old Fluke 97 without probes for a fair price.

I’ve already bought a Fluke PM9082 adapter and a Fluke 80i-410 AC/DC clamp meter.

My main use case as a hobbyist is watching startup currents on generator starter motors and some UPS battery load monitoring but I’m also looking to assess governor response time on 120/240VAC generators (portable and non) as well as assessing power condition from car inverters, power conditioning UPSes etc. So all 60hz mains.

What probes should I look for to maximize safety? I realize I need insulated BNC due to misconnecting grounds, probably 10x but what else? I’ve seen the warnings in the Fluke 97 manual and am digesting what they mean for probes and use in practise. All of my testing will be downstream of tested GFCIs and I’m considering using step down AC transformers. Would an AC transformer mask the waveform issues?

I’m wondering if I can do my testing with the 9082 and existing multimeter probes as I’m looking at pretty low frequency stuff
« Last Edit: April 14, 2022, 08:57:00 pm by Flukenewbie »
 

Offline bdunham7

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Re: Portable oscilloscope probes for measuring mains
« Reply #1 on: April 14, 2022, 09:28:20 pm »
The original Fluke probes and accessories that came with Scopemeters were pretty nice.  There's a pair of "PM9818" probes on eBay right now for $70, but you need to ask exactly what they are because those came in a variety of flavors.  You do want the 10X full-bandwidth version, IMO.  They made a 4kHz 'filter-probe' version as well.  Otherwise, any well-insulated (no metal exposed) 10x probe will suffice, but I have found that some non-insulated probes do not make proper contact with the insulated BNCs on the Flukes.

Keep in mind that the Fluke 97 is isolated, but the channel grounds are not isolated from each other.  One way to avoid catastrophe is to only use one of the ground leads.

https://www.ebay.com/itm/255442714024?hash=item3b79927da8:g:ZDEAAOSw5UtiNOpE
« Last Edit: April 14, 2022, 09:32:35 pm by bdunham7 »
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline chinoy

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Re: Portable oscilloscope probes for measuring mains
« Reply #2 on: April 22, 2022, 05:20:58 am »
I have owned a few of the fluke portable scopes. My last one was the 105B.
Your best bet is to keep an eye out on ebay and other sites selling used gear.
I remember getting a huge bundle of Fluke probes, for like 40$. There were over 20 probes, convertors, even a high voltage probe.
The best part all had stickers on them indicating the date they were last calibrated.
Buying anything fluke new is way outside my budget.
If I had to recommend one probe to check out it would be the high KV probe. It can handle upto 6000 volts.
Other than that get some 100 Mhz regular 10x probes.
Its a bad idea to use a fluke with a cheap probe.
Even though I now own a Hantek I still use my Fluke 105B when I want accuracy.
Most of my work is done in the 0-1 Volt range and I have like 2 Scopes and 5 multi meters to measure and no two meters give me the same numbers. So I trust my fluke values over all the other gear. The only problem is the plastic on these scopes degrade with time and everything starts to fall to bits with age.
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Offline Terry Bites

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