Oscilloscope for Power Generation - Page 1
Forum section: electronics / testgear

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 08:35:01 pm
content: Hi y'all,I work as a field tech in the emergency power generation field. I've recently had a couple jobs where viewing the waveform at hand would have been useful, mainly when troubleshooting, or doing a conversion of automatic voltage regulators (AVR). The power measured is 240, 277, or 480vac. My question is: does anyone here have experience or recommendations when choosing a field oscilloscope? I'm going back and forth between using a bench scope with a HV probe, or forking out the cash for a "scope meter". My main concern with the bench scope is the environment, since it's often hot, humid, rainy, or just plain dirty in this field.I'm open to any suggestions you may have, and hope to get a discussion going here. I checked to see if this question had been asked but mostly saw field scope discussions based around low voltage dc measurements for the automotive sector.Thanks!

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 09:02:59 pm
content: I'd be interested to hear real world experience with some meter reviews as well.In all likelyhood, if the equipment has the proper ratings and isn't a piece of junk, it should suffice.The latest and greatest fluke 190-XXX series scopemeters are big money, and out of the range of anyone who doesn't have a company purchase it for them (unless they're bananas or work for themselves). They're rated at CATIV 600V - CATIII 1000V. which is as good as it gets right now. the older version like the 123-4-5, 192-196-199, etc all seem to be rated at CATIII 600V - CATII 1000v, which was the previous standard but apparently just as good for medium voltage work, as that's what every scope from that era was rated.I looked at the THS3000, and a few other scopes people have relied on over the years and they all carry the same ratings.The one I settled on has the rating for CATIII 600V - CATII 1000V like the previous flukes, and even uses the same HV 10:1 probes that the flukes have (made by multi-contact/staubli), the SHS1062... unfortunately I don't know much about it because there isn't much information about it out there, but Siglent seems to make a good product, have UL listings, and even send high end probes with it..... so your take is as good as mine.

author: 2N3055
author_rank: Super Contributor
timestamp: February 12, 2022, 09:10:11 pm
content: Quote from: akimbojimbo on February 12, 2022, 08:35:01 pmA "scopemeter" type of instrument seems to be best bet for you. Also 480V environment is already dangerous and instrument designed for that should be used.Maybe one of the power analyzers ?If you want to go with scopes, apart from Fluke, Keysight and R&S , there are Siglent and Micsig that make scopes in that format with isolated channels and safe to use for mid voltage. Take a look at datasheets.

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 09:21:32 pm
content: I have been eyeing the Siglent handhelds as well. Have you liked it so far, or not enough time in the saddle with it yet? It seems like power generation work with scopes is a kind of oddball field, with everyone deferring to the Flukes (which like you said, is crazy money). The handhelds are what I'm leaning towards: not needing an outlet, less cables to get tangled up, hopefully more resistant to poor environments, etc.Both Siglent and Tektronix seem like they will be my best bet, having both the right specs, and a name that I know I can reasonably trust. It might be silly, but I'm not interested in checking mains power with a no-name USB scope or the like - especially when I'm being paid to do so. I have tried rationalizing the Fluke cost, thinking it will be an "investment" for consulting in the future (just like my desire to pick up a Megger), but I think that's more a discussion for the Test Equipment Anonymous threadSide note, I've only ever used Satubli for their dry break/quick disconnect fittings. I had no idea they made probes

author: nctnico
author_rank: Super Contributor
timestamp: February 12, 2022, 09:21:47 pm
content: One thing to watch out for with handheld oscilloscopes is that there are many models (usually the cheaper models) that do not have CAT rated isolated inputs. Typically: if isolated inputs are not mentioned as a feature, the oscilloscope does not have CAT rated isolated inputs.

author: bdunham7
author_rank: Super Contributor
timestamp: February 12, 2022, 09:22:49 pm
content: If it were me I'd just fork out the bucks for a Fluke 190-series Scopemeter. If your generators are not 3-phase, the two-channel 60MHz version will do, and you probably will want the current clamp accessories to look at power. If you do three-phase, then perhaps the 100MHz 4-channel model might be what you want, although obviously you can't do 3 phases of both current and voltage. The 2 and 4 channel models have some other differences as well--for instance the 2 channel has a separate DMM/banana jack input and an external trigger, the 4 channel doesn't.There are other options, but I don't think any of them work as well. If you have a tight budget, perhaps a used or older-model Scopemeter will do. The Tektronix TPS-series lunchbox sized scopes are one choice for HV-isolated bench work, but they aren't all that rugged and they end up getting beat up pretty badly in the field. They also are not cheap. Rohde and Schwarz makes a series of handhelds that are considered better scopes than the Fluke in many ways--they are a newer design and have more modern DSO features--but they aren't giving them away either.I think the main advantage of the Fluke models is that they were specifically made for applications just like yours. 30 years ago I purchased one of the first-generation Fluke Scopemeters for use in the automotive industry. It cost me about a month of net wages. I still have it, it still works, and although it is an extremely limited scope by general-purpose standards it served me quite well for many years and I never regretted spending the money.

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 09:25:37 pm
content: No, Haven't used it in field work yet (Industrial Controls/systems integration and service). I've only hooked it up to some 1PH -> 3PH vfd to test the display and capture/update rate. it looks as good as my benchtop that i've messed with, so only time will tell.

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 09:28:58 pm
content: Quote from: 2N3055 on February 12, 2022, 09:10:11 pmYeah, most of my research keeps cycling back to the scopemeters or PQ analyzers. Just at the moment, I can't rationalize spending $3000+ on a single piece of gear - down the road, sure. However, you bring up a good point with the analyzers. I had already identified a need for one of those, so a tool that would do both PQ datalogging and function as a scope would be ideal. Only issue is, during long term power studies I would be without the scope. A couple of customers have been having issues with supposed utility power quality confusing the ATS and calling the generator to start randomly throughout the week, so it would be tied up at those locations for a good amount of time.

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 09:29:31 pm
content: Quote from: bdunham7 on February 12, 2022, 09:22:49 pmIn the years i've been working with 480v 3phase, and 480v inverters, I've never had to ever resort to trying to view all 3 phases at a time. From my knowledge, that kind of feature is reserved for companies that sell power analyzing as a product, and not as a troubleshooting tool. the worst things get is a lower DC bus voltage than expected, which can even be viewed with an 87v in peak-min/max mode when looking at the incoming 480.

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 09:33:46 pm
content: Quote from: bdunham7 on February 12, 2022, 09:22:49 pmAll equipment I work on is three phase, so the 4 channel would be my best bet. It's good to hear your scopemeter is still going strong, I'd hate to spend - like you said, a months wages - only to have it be obsolete or a brick within a handful of years. I will certainly check out the Rohde & Schwarz offerings, I haven't seen them before. All good points to consider, thank you!

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 09:36:23 pm
content: Quote from: ControlsLost on February 12, 2022, 09:29:31 pmMy thoughts on monitoring all three phases at once are mainly AVR related. Especially when doing a conversion, the sensing circuits can be a right PITA.

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 09:41:59 pm
content: Quote from: akimbojimbo on February 12, 2022, 09:36:23 pmgood point, the most I do with generators is the controls aspect. I had dealt with a datacenter generator not starting up properly when it needed to. cause was 35v being sent to the 24v PLC power causing it to glitch out when the generator was brought into line. Charging circuit issue. I wouldn't be the one going out to diagnose why the generator power wasn't clean enough.

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 09:53:51 pm
content: Quote from: ControlsLost on February 12, 2022, 09:41:59 pmThat's an area that I'm still trying to sort out. Being an independent service company, we deal with all makes and models of generators and controllers, as well as ATSs. It's been a steep learning curve coming from the powersports sector, but very interesting. Surprising how quick you can go from just needing a 117 DMM to equipment well into the thousands.I am interested to see if a PQ analyzer would suffice the oscilloscope need as well, though. I'll have to do some digging about that.

author: nctnico
author_rank: Super Contributor
timestamp: February 12, 2022, 10:08:39 pm
content: Quote from: akimbojimbo on February 12, 2022, 09:53:51 pmYep. Been there as well. You think you have a whole bunch of equipment but the next project that comes along needs a type of measurement you are not equiped for. Just spend your money wisely. Buying used (from a reputable test equipment dealer) is an option you should consider as well. And I don't mean buying 20+ year old boat anchors that need a lot of fixing but equipment that is a couple of years old or just surplus. In the past couple of years I scored some excellent deals for equipment that was in as-new / unused condition and even had some manufacturer warranty left.

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 10:17:24 pm
content: That's definitely something I have to open up too. In past experience I've come across verified good used equipment being as much as ~80% of the retail new cost, and when spending that kind of money already, I just cant get myself to go for something that I don't know the history of. But, I will certainly keep my eyes open there.It's an affliction I haven't quite gotten used too. Nothing worse than being in the field, knowing what kind of measurement or data you need to fix or explain to the customer, but you don't have the tool. My management's solution is usually to BS the customer/blindly change parts, but it doesn't sit right with me knowing I could have easily done better.

author: threephase
author_rank: Regular Contributor
timestamp: February 12, 2022, 10:55:26 pm
content: Unless you have a really high spec PQ analyser, they don't really provide the functionality that an oscilloscope offers. They are very good at what they do, i.e providing data over extended periods of time for voltage current harmonics etc, but they just don't offer the sane control for signal viewing as a scope does. You can always hire in a PQ analyser if they are not used that often, or get the customer to hire it in and do the data collection / analysis for them.I used a Keysight U1602 scope meter as a general oscilloscope for capturing signals and then a Hioki HiCorder unit for 3 phase / AVR / synchroniser work. That also provided digital as well as analogue channels. There are plenty of other DAQ systems out there besides Hioki and may be worth looking at.It is also worth looking at the protection relays that are installed if you are working on modern systems, as the numerical protection relays usually offer measurements and fault data capture / analysis. You can also use them with the software for long term trending. You could probably even mount one in a case and use it as a portable data recorder if you had one available. It won't suffice as a scope though, to get waveforms out you usually have to save the data and look at it in the software.

author: akimbojimbo
author_rank: Contributor
timestamp: February 12, 2022, 11:33:11 pm
content: Quote from: threephase on February 12, 2022, 10:55:26 pmThe protection relay is a great idea, at least for longer term studies. It's looking like a handheld, portable "scopemeter" style of instrument is going to be the way to go for me. And if I am already going to be shelling out thousands for one, I figure I might as well go for a good name brand, with decent measurement confidence and the like - at least when doing customer jobs. It also looks like the PQ analyzer will be a separate purchase, far down the road..Thank you all for the input! I hope this discussion can keep going, as I'm always interested to hear other's experiences in the field with different instruments.

author: Martin72
author_rank: Super Contributor
timestamp: February 12, 2022, 11:53:17 pm
content: Quote from: nctnico on February 12, 2022, 09:21:47 pmAlso "typically": The price.Handheld-Scope(-Meters) s are more than enough on the market, but when the channels should be isolated, the price will "explode".For example, Siglent...2-Ch, non-isolated, 100Mhz, SH810:https://www.welectron.com/Siglent-SHS800-Hand-Oszilloskop-Serie570€2-Ch, isolated, 100Mhz, SHS1102:https://www.welectron.com/Siglent-SHS1000-Hand-Oszilloskop-Serie1674€.....Last week, a SHS1102 arrived at work - We´ve order one for testing for the service-crew.Display was a little bit "surprising" and FFT wasn´t that easy to adjust, but overall it looks nice.Got recorder function, we will test it in the near future.

author: tautech
author_rank: Super Contributor
timestamp: February 13, 2022, 01:34:40 am
content: Quote from: Martin72 on February 12, 2022, 11:53:17 pmOh shame you had to move so soon as new models are coming:https://www.eevblog.com/forum/testgear/new-x-model-siglent-handhelds-coming/

author: ControlsLost
author_rank: Contributor
timestamp: February 13, 2022, 02:06:50 am
content: looks great that they're coming out with improvements, the SHS1000 series was listed as discontinued on their website. I wonder what the price difference will be though. Especially after the success of the 800 series and the current markets, is it really feasile that the isolated version will remain under 2k price range?

author: tautech
author_rank: Super Contributor
timestamp: February 13, 2022, 02:21:47 am
content: Quote from: ControlsLost on February 13, 2022, 02:06:50 amI suspect they will. Yes they were marked as discontinued however now EOL so maybe another production run was done.Current pricing for the 100 MHz SHS1102 is $1,526 ....the new 200 MHz SHS1202X model maybe not.https://siglentna.com/handheld-oscilloscopes/shs1000-series-isolated-handheld-digital-oscilloscopes/

author: ControlsLost
author_rank: Contributor
timestamp: February 13, 2022, 02:25:18 am
content: that would be interesting. I just purchased a 1062, everything I'm worried about is in the 60hz-30khz range. I'm tempted to just return this one and wait for the newest version though, but I wouldn't be happy if i had a 1250 dollar purchase turn into a 1700 dollar purchase just to get some decoding features i wouldn't use.. (I use rs485, rs232, and other protocol on controls communications, but i have no need to try to debug or watch them for any reason, aside from using a usb-rs232 that shows all input and output through it).

author: geggi1
author_rank: Frequent Contributor
timestamp: February 13, 2022, 07:24:56 am
content: If working with 3 phase you should go for a PQA because then you got 3 chanels for voltage an 3 for current.You will also get measurements of THD that can be important when working with generators.

author: Martin72
author_rank: Super Contributor
timestamp: February 13, 2022, 11:23:52 am
content: Quote from: tautech on February 13, 2022, 01:34:40 amBut if this one will fulfill our needs, it won´t be the only portable siglent scope here.

author: akimbojimbo
author_rank: Contributor
timestamp: February 13, 2022, 06:58:37 pm
content: Quote from: geggi1 on February 13, 2022, 07:24:56 amI have been considering that route as well. However, my concern with the PQ analyzer is it's ability to set triggers as well as be used on low voltage control circuits.. But don't get me wrong, the analyzer would certainly be all around useful for the THD aspect, as well as fault finding on ATSs.While I did start this thread based on the power aspect of generation, I am still looking for functionality on the low voltage control side.