Oscilloscope for AC work ?

[SND]

I need a good safe way to check harmonics, THD and wave form on 120 and 240V  1ph 60hz circuit, with possibly up to 125A/1ph breaker on them. I expect the main harmonic to be about 5khz but there could be other stuff in there, higher or lower.(IGBT/VFD's)   Most of this will be done at the panel, and input of a few units.

I may like to be able to check some 3phase 60hz wave form as well and what harmonics might be going on there but its less important.
I can probably stick to just doing each leg to ground on their own but if its possible to go leg to leg then great. I'm still reading/learning about what these oscilloscopes can/can't do, but I do well know the dangers of the electricity I'm dealing with
. 
Would the Siglent SDS1202X-E or SDS1104X-E be a good choice for this application?  Are the probes that come with it ok for this? I see they're just 10x probes. Should they be upgraded to something else and if so, which?
I also read a bit into the Hantek DSO-8060 handheld unit, looks interesting but I'm not sure if that's a better or worse choice.
I want something reliable and accurate enough that will last many years as I will need to check the THD levels periodically.

Are there any other units and accessories perhaps better suited for this that you'd recommend?

thanks

[DDunfield]

Any time you want to scope mains (especially across phases) you don't want to use a typical grounded scope.

I would recommend battery powered scopemeter certified for the voltages and type of circuits you will be connecting to.

Exactly which one to recommend depends on your budget and needs. Do you need more one channel?  Do you need advanced math FFT etc. Ability to upload waveforms to PC for analysis?
Fluke has some very nice offerings including a specialized "motor driver analyzer" series with harmonic measurements etc. -- warning - they're not cheap!

Dave

[woodchips]

Look for a Powerscope, I have an 881 Mk2.

These are made in Australia and are specifically intended for AC mains power work, 400V input on all channels.

They are now old and quite rare, download a copy of the manual to see what it does.

[Jwillis]

Another way is to use a 100:1 probe or High Voltage Differential Probe.All depends or how high a voltage you intend on scoping.Running your scope from an isolation transformer might  be a good idea .Maybe someone could comment on that idea.

[bdunham7]

Is this a utility-fed mains circuit?  Or some type of generator/solar system?  Where is a 5KHz 'harmonic' coming from?

You need specialized equipment to do this safely.  My choice would be some flavor of Fluke Scopemeter, especially since they often come with excellent leads and probes.  There's no call for poking around in utility panels with cheap (or even expensive) regular oscilloscopes and their related probes.  There's just too many things that can go way wrong way too fast.

[tggzzz]

Another way is to use a 100:1 probe or High Voltage Differential Probe.All depends or how high a voltage you intend on scoping.Running your scope from an isolation transformer might  be a good idea .Maybe someone could comment on that idea.

All those ideas are dangerous in one way/situation or another.

For a longer discussion, see the many other threads on the topic.

[Benta]

Another way is to use a 100:1 probe or High Voltage Differential Probe.All depends or how high a voltage you intend on scoping.Running your scope from an isolation transformer might  be a good idea .Maybe someone could comment on that idea.

All those ideas are dangerous in one way/situation or another.

For a longer discussion, see the many other threads on the topic.

I fully agree.
The only correct way of measuring mains on a 'scope is using high voltage differential probes. Everything else is a recipe for killing yourself.
Don't even think about battery 'scopes or isolation transformers.

[SND]

I read up a bit more and watched a few more videos about what these can and can't do. 120vac is all I really got to worry about for voltage, just leg to ground and it is power from the pole. 
I can do each leg one at a time and I got room in there to work anyhow, I'm pretty used to working with live AC 1 and 3ph.
I mostly need it to check a wide enough spectrum of harmonics on the power line which it seems the FFT function should do. Find the worst frequencies, and have it give me a THD %.   Since most of these oscilloscopes like the SDS1104X have a FFT math function, can I assume they also have a button that adds it all to a THD %? 
I did think that the ground could be an issue as I'm pretty sure there's some noise on it from the units I want to test, but that might be fine as it's really to establish a baseline anyway.
I've no intention to try to run a plug in oscilloscope unit without a ground that's for sure... did notice some pretty sketchy setups while reading and checking youtube...

The battery scopes like the siglent 810 and hantek's don't see to get the best reviews and I have no use for their multi-meter side. A fluke 125b could be nice for at almost $4k, hard to justify for this.

[tautech]

I read up a bit more and watched a few more videos about what these can and can't do. 120vac is all I really got to worry about for voltage, just leg to ground and it is power from the pole. 
I can do each leg one at a time and I got room in there to work anyhow, I'm pretty used to working with live AC 1 and 3ph.
I mostly need it to check a wide enough spectrum of harmonics on the power line which it seems the FFT function should do. Find the worst frequencies, and have it give me a THD %.   Since most of these oscilloscopes like the SDS1104X have a FFT math function, can I assume they also have a button that adds it all to a THD %? 
I did think that the ground could be an issue as I'm pretty sure there's some noise on it from the units I want to test, but that might be fine as it's really to establish a baseline anyway.
I'd no intention to try to run a plug it unit without a ground that's for sure... did notice some pretty sketchy setups while reading and checking youtune.

The battery scopes like the siglent 810 and hantek's don't see to get the best reviews and I have no use for their multi-meter side. A fluke 125b could be nice for at almost $4k, hard to justify for this.

It's not wise to use stock 10x probes for mains use as a matter of course. 100x probes aren't expensive and offer higher voltage ratings and additional protection from surges.
Still, for regular use on mains it's better to use a HV differential probe and negate any risk of ground loops.

I don't see any provision for THD measurements in the Datasheet so interpretation of the FFT seems the only way with an SDS1104X-E.
https://www.siglentamerica.com/wp-content/uploads/dlm_uploads/2018/05/SDS1000X-E_DataSheet_DS0101E-E03B.pdf

[SND]

I look a bit more into the HV differential probes,  any brand/model in particular to consider?

[tautech]

I look a bit more into the HV differential probes,  any brand/model in particular to consider?

Pintek DP-25 is a good entry level diff probe

Others:
Micsig
EEVblog

[DDunfield]

Not running a bench scope without a ground is the right attitude, but unless you have a differential probe, it means that all of your measurements will be referenced to ground. You won't be looking across 3 phases properly, and even single-phase properly between neutral and hot.

You can make use of differential readings to use two channels as a single differential input with normal probes, but this is usually considered a MATH function, and doing so may prevent you from performing other match function which may include FFT on some scopes. Differential probe is a much better way.

Scopes with integrated power THD measurements are not common. I believe some of the Fluke MDA series I mentioned earlier do perform a THD measurement, but for the higher end models you are getting up $10k+  (at least in Canuck bucks). Would it be an option to use a device that can store waveforms and upload to a PC later for detailed analysis later?

Someone mentioned using 100x probe - good idea. If you decide to get away with 10x which *should* be ok for 120v circuits, DON'T use a 1x/10x switchable probe! - they WILL get switched and bad things will happen!

[rstofer]

I look a bit more into the HV differential probes,  any brand/model in particular to consider?

Our host makes one

https://www.eevblog.com/product/hvp70/

It is not in stock but maybe that is negotiable.  You can also use it as a frame of reference.

In industry, were we to make such measurements, we would need the full complement of Personal Protective Equipment (PPE) including flame retardant overalls, face shield, rated low voltage gloves and we would probably stand on an insulating mat.

[bob91343]

For many purposes, one can simply put a decent quality transformer on the mains and look at the secondary with ordinary precautions.  Of course the transformer will distort the wave but it might not be serious, depending on what you are trying to do.

You could also try a couple of different transformers and see how the results compare.  But most power line transformers won't have a lot of response into the kHz region.

Another type of transformer that might be better is an output transformer from an old tube type hi-fi amplifier.  They usually can handle the voltage and are wound with more care.

[bdunham7]

I fully agree.
The only correct way of measuring mains on a 'scope is using high voltage differential probes. Everything else is a recipe for killing yourself.
Don't even think about battery 'scopes or isolation transformers.

First, make sure that your differential probe is specifically suited for the task (CAT III or IV rated in this case) and remember that they are not completely isolated and have non-trivial input loads in some cases.

Second, why do you dismiss battery operated scopes?  A proper one is as safe as a proper DMM, and if you showed up as an electrician to work in a panel with anything else you'd be thrown out. 
 

[rsjsouza]

As others have mentioned, you really can't go wrong with a CAT III or CAT IV rated scope such as:
https://www.fluke.com/en-us/product/electrical-testing/portable-oscilloscopes/190-series-ii/fluke-190-ii-190-102-s

(edit) but perhaps something a bit cheaper but still reputable could be this Chauvin Arnoux:
https://www.aemc.com/products/oscilloscopes/oscilloscope-ox5022

[tautech]

I fully agree.
The only correct way of measuring mains on a 'scope is using high voltage differential probes. Everything else is a recipe for killing yourself.
Don't even think about battery 'scopes or isolation transformers.

First, make sure that your differential probe is specifically suited for the task (CAT III or IV rated in this case) and remember that they are not completely isolated and have non-trivial input loads in some cases.

Second, why do you dismiss battery operated scopes?  A proper one is as safe as a proper DMM, and if you showed up as an electrician to work in a panel with anything else you'd be thrown out.

Unless they offer isolation for all channels and normally they only offer proper isolation for one channel before getting into the old ground loop scenario. 
Fully independent isolated channel scopes, handheld or bench top units are $ $ $.

[rsjsouza]

I fully agree.
The only correct way of measuring mains on a 'scope is using high voltage differential probes. Everything else is a recipe for killing yourself.
Don't even think about battery 'scopes or isolation transformers.

First, make sure that your differential probe is specifically suited for the task (CAT III or IV rated in this case) and remember that they are not completely isolated and have non-trivial input loads in some cases.

Second, why do you dismiss battery operated scopes?  A proper one is as safe as a proper DMM, and if you showed up as an electrician to work in a panel with anything else you'd be thrown out.

Unless they offer isolation for all channels and normally they only offer proper isolation for one channel before getting into the old ground loop scenario. 
Fully independent isolated channel scopes, handheld or bench top units are $ $ $.

Exactly. The OP's specs simply have way too much energy to fool around with cheaper alternatives.

[bdunham7]

Unless they offer isolation for all channels and normally they only offer proper isolation for one channel before getting into the old ground loop scenario. 
Fully independent isolated channel scopes, handheld or bench top units are $ $ $.

I would think that one channel at a time would be a given unless you have an instrument specifically designed for 3-phase power analysis--and I think that would be way beyond the OP's needs.  Using only one ground lead is standard ScopeMeter technique.  I suppose three HV differential probes would get the job done, but who has that?

[tautech]

Unless they offer isolation for all channels and normally they only offer proper isolation for one channel before getting into the old ground loop scenario. 
Fully independent isolated channel scopes, handheld or bench top units are $ $ $.

I would think that one channel at a time would be a given unless you have an instrument specifically designed for 3-phase power analysis--and I think that would be way beyond the OP's needs. 

Not so much.
While not as good as an differential probe Siglent's ISFE works OK and offers 2 isolated channels:
https://www.siglentamerica.com/accessory/isolated-channel-optional-accessories%EF%BC%88isfe%EF%BC%89/
Note, the BNC spacings and F-F adapters are such to fit directly onto any Siglent DSO and that may not allow other brands connection without additional BNC leads.

Using only one ground lead is standard ScopeMeter technique.  I suppose three HV differential probes would get the job done, but who has that?

Those that want to view 3 phase mains with entry level equipment.
Cheap 4ch DSO + 3 differential probes is still cheaper than any isolated channel scope, HH or bench top.

[joeqsmith]

They certainly do make equipment just for this purpose.  The one I use can measure all three phases, both current and voltage plus a spare channel.   I would recommend you talk with some of the sales reps and have them bring in there systems for a demo.   

Several companies offer them with various features depending what you need.  For example:

https://www.testequity.com/products/33042/

[Benta]

Second, why do you dismiss battery operated scopes?  A proper one is as safe as a proper DMM, and if you showed up as an electrician to work in a panel with anything else you'd be thrown out.

No it's not.
Hint: look at the connectors:
DMM: fully shrouded with properly isolated test leads.
'Scope: exposed BNC and (thin) probe cables with insufficient insulation.

Generally: Do not let your test equipment carry mains voltage unless it's specifically designed for it.

[SND]

Thanks for all the replies.
I'm currently considering the AEMC 407 clamp meter, with their free bluetooth software it might get me close enough to what I'm trying to find, at least it has some THD functions. I'm not 100% sure it'll get to the higher frequencies that might be in there but for a bit over $500 could be worth a try.

[DDunfield]

Second, why do you dismiss battery operated scopes?  A proper one is as safe as a proper DMM, and if you showed up as an electrician to work in a panel with anything else you'd be thrown out.

No it's not.
Hint: look at the connectors:

Yes it is.
Hint: look at the connectors!

Discussing a "proper" battery powered scope (Scopemeter) ... Like a Fluke, not DSO-xxx hobby class rubbish.

My Fluke has the inputs (including the BNC's) insulated so that you cannot contact metal, even on an unconnected BNC socket. The probes are fully insulated, no metal of the BNC is exposed.
Bare input on the scope is rated max. 300v (4kv surge). With the standard 10x probe, it's rated 600v (6kv surge).
HV probes are available which are rated for many kv - Highest input range in scope mode, configured with a 1000x HV probe is 100kv!

And, yes .. I agree, if you showed up to my building planning to look at my 3 phase mains, or VFD outputs with a typical bench scope, I'd send you packing.

Dave

[rsjsouza]

Second, why do you dismiss battery operated scopes?  A proper one is as safe as a proper DMM, and if you showed up as an electrician to work in a panel with anything else you'd be thrown out.

No it's not.
Hint: look at the connectors:

Yes it is.
Hint: look at the connectors!

Exactly: