User Panel
User Panel
User Panel
|
Posted: 6/24/2021 1:53:29 PM EDT
[#1]
Not going to comment on the scope as I don't know the answer. But for the inverter generator I wonder if you need a load on it, even a small one, to stabilize the output? Just a WAG...
|
|
|
|
Posted: 6/24/2021 1:57:38 PM EDT
[#2]
do not under any circumstances connect the scope probes directly to the the generator/inverter output.
you can damage the scope and damage yourself. |
|
|
|
Posted: 6/24/2021 6:00:51 PM EDT
[#3]
Quote HistoryQuoted: do not under any circumstances connect the scope probes directly to the the generator/inverter output. you can damage the scope and damage yourself. This x1000. The alligator clip dangling from the scope's probe is connected to AC mains safety ground. |
|
|
|
Posted: 6/24/2021 7:03:24 PM EDT
[#4]
The simplest solution is to connect the generator to the 120 VAC terminals of a 16 VAC doorbell transformer, and then connect the scope to the transformer's 16 VAC output terminals.
The transformer serves two purposes: It reduces the generator's AC output to a voltage the scope can safely handle, and it prevents ground loops (i.e., isolates the generator's neutral connection from the scope's ground connection). |
|
|
|
Posted: 6/24/2021 8:00:33 PM EDT
[#5]
Quote HistoryQuoted: do not under any circumstances connect the scope probes directly to the the generator/inverter output. you can damage the scope and damage yourself. Really? I used to do this all of the time with the scope that we have at work. I should try to find the specs on that one to see what the input voltage is rated for. I am not sure that I will be able to Google it. That scope was old when I started working there over twenty-five years ago..... But hooking it up to a smaller transformer is a good idea. Step the voltage down to a safer level without sacrificing the wave form. |
|
|
|
Posted: 6/27/2021 4:00:03 PM EDT
[#6]
Quote HistoryQuoted: The simplest solution is to connect the generator to the 120 VAC terminals of a 16 VAC doorbell transformer, and then connect the scope to the transformer's 16 VAC output terminals. The transformer serves two purposes: It reduces the generator's AC output to a voltage the scope can safely handle, and it prevents ground loops (i.e., isolates the generator's neutral connection from the scope's ground connection). Just make damn sure you connect the transformer up the correct direction 120 to 16 VAC transformer becomes a 120 to 900 VAC transformer if connected backwards. The best thing to do is just go buy a 10X probe. This will bring the 120VAC down to 12VAC and make it generally safe for the scope input. |
|
|
|
Posted: 6/27/2021 8:27:29 PM EDT
[#7]
Thanks, guys. I wasn't sure what I was doing and I wanted to make sure I didn't fry my scope, or myself. I was able to attach the plug to a spare USB a/c charger and get my readings. I encountered a strange issue that I could really use some help with.
The Wen unit I tested was fine. Very nice, smooth sine wave. No issues at all using it for anything. I also have a Champion 200913 open frame inverter. I tested it on the scope as well. I was expecting the same sine wave that I got with my Wen. But what I got was this:  I tested several, different ways. From the outlet direct, from an extension cord, from a surge protector, the same waveform. However, when I plugged in one of those bonded-neutral plugs, I got a regular, normal sine wave like the Wen. So, why would the signal out the box look so bad like that, and why would a bonded-neutral plug clean it up? My thought is that there may be some grounding issue someplace. Is that possible? I'm really stumped on this one. |
|
|
|
Posted: 6/27/2021 8:30:08 PM EDT
[#8]
Once I plugged in that bonded neutral I just told you about, this is what the waveform looked like:
 I would think that the Champion inverter would look like that without having to use a special plug. It's got a floating neutral, but so does the Wen and the Wen looked fine without any plugs. |
|
|
|
Posted: 6/28/2021 12:29:54 AM EDT
[#9]
Quote HistoryQuoted: I was able to attach the plug to a spare USB a/c charger and get my readings. what does this mean? |
|
|
|
Posted: 6/28/2021 1:17:06 AM EDT
[#10]
Quote HistoryQuoted: do not under any circumstances connect the scope probes directly to the the generator/inverter output. you can damage the scope and damage yourself. From the Amazon link the OP provided there is a picture of the supplied probes and it has a 1x/10x switch in the body of the probe. You don't think it would be safe to attach the positive lead to the 120VAC hot leg with the probe in the 10x position? If not why? |
|
|
|
Posted: 6/28/2021 6:37:20 AM EDT
[#11]
Quote HistoryQuoted: what does this mean? I used to hot leg of a USB charger plug. |
|
|
|
Posted: 6/28/2021 4:08:00 PM EDT
[#12]
A scope, or in your case a DSO (digital storage oscilloscope) measure voltage over time.
That is all it does. The measurement of voltage is a measurement of difference in potential, essentially. What is the potential difference at the point of the probe compared to the reference. The reference is that short little alligator clip on the probe. If you had nothing to measure reference to (your alligator clip is just dangling in air), your reference was "floating" and giving you crap data. Once you secured a reference, you were GTG and got a true measurement. |
|
|
|
Posted: 6/28/2021 4:09:40 PM EDT
[#13]
Quote HistoryQuoted: do not under any circumstances connect the scope probes directly to the the generator/inverter output. you can damage the scope and damage yourself. 
|
|
|
|
Posted: 6/28/2021 7:34:12 PM EDT
[#14]
Quote HistoryQuoted: A scope, or in your case a DSO (digital storage oscilloscope) measure voltage over time. That is all it does. The measurement of voltage is a measurement of difference in potential, essentially. What is the potential difference at the point of the probe compared to the reference. The reference is that short little alligator clip on the probe. If you had nothing to measure reference to (your alligator clip is just dangling in air), your reference was "floating" and giving you crap data. Once you secured a reference, you were GTG and got a true measurement. Yeah, I was finally able to get some readings. What surprised me was the fact that my Champion inverter was making some weird looking waveforms until I bonded the neutral. I was expecting the waveform to look good bonded or floating. I haven't been able to figure that one out. |
|
|
|
Posted: 6/29/2021 7:08:18 PM EDT
[#15]
I was able to reach Champion tech support this morning. They are sending me a new fuel valve to replace the leaking one. I asked him about the strange scope readings I posted here. He asked how I was testing the signal and I told him I was clipping onto the hot leg of a plug. He said that to get an accurate reading on Champion inverters, I need to ground the probe connection. He said that attaching only to the hot leg and no ground was going to give a noisy reading. That's why when I bonded the neutral, I was then showing a clean sine wave. So, according to his explanation, it was a instrumentation issue since I was attaching, ungrounded, on the hot leg.
|
|
|
|
Posted: 7/1/2021 3:00:42 PM EDT
[#16]
Quote HistoryQuoted: Why not? I see the scope is rated for 300v, and I would ASSume the scope has leads that match/exceed that, so there shouldn't be an issue at all, other than you are playing with mains voltage that can kill you if you touch a no-no Quote HistoryQuoted: Quoted: do not under any circumstances connect the scope probes directly to the the generator/inverter output. you can damage the scope and damage yourself. This is a common mistake new 'scope users make. The common/ground lead of each probe is connected to the common lead of the other probes AND the chassis of the scope, which is grounded to earth. Some folks measure floating ground devices without blowing up the scope, but if the generator is make contact with the ground, you can form a ground loop amd shock yourself or blow up the scope. The acceptable way to measure mains voltage is with a differential probe. Also keep in mind 120Vac is 120 V RMS, which is 343 Vp-p |
|
|
|
Posted: 7/1/2021 3:28:50 PM EDT
[#17]
Quote HistoryQuoted: This is a common mistake new 'scope users make. The common/ground lead of each probe is connected to the common lead of the other probes AND the chassis of the scope, which is grounded to earth. Some folks measure floating ground devices without blowing up the scope, but if the generator is make contact with the ground, you can form a ground loop amd shock yourself or blow up the scope. The acceptable way to measure mains voltage is with a differential probe. Also keep in mind 120Vac is 120 V RMS, which is 343 Vp-p Shows how often I play with AC mains voltage on my scope 
|
|
|
|
Posted: 7/1/2021 3:41:19 PM EDT
[#18]
Don't go messing with mains voltage without using a Differential Probe.
Like this one...  Seen too many college grads almost kill themselves in the lab while poking around a power supply. |
|
|
|
Posted: 7/1/2021 8:48:21 PM EDT
[#19]
Would bonding the neutral eliminate the risk of a ground loop?
|
|
|
|
Posted: 7/1/2021 9:57:13 PM EDT
[#20]
Quote HistoryQuoted: Would bonding the neutral eliminate the risk of a ground loop? Nope, it would help guarentee a ground loop. Right way is with a differential probe. |
|
|
|
Posted: 7/2/2021 7:18:47 AM EDT
[#21]
Quote HistoryQuoted: Nope, it would help guarentee a ground loop. Right way is with a differential probe. The differential probes, as they they only way to be completely safe? The ones I saw were major $$$. A simple ground wouldn't suffice? |
|
|
|
Posted: 7/2/2021 3:56:13 PM EDT
[#22]
Quote HistoryQuoted: The differential probes, as they they only way to be completely safe? The ones I saw were major $$$. A simple ground wouldn't suffice? I used this probe Probe. $168 
|
|
|
|
Posted: 7/3/2021 8:45:08 AM EDT
[#23]
Quote HistoryQuoted: I used this probe Probe. $168 https://images-na.ssl-images-amazon.com/images/I/61-IYcHdiZL._AC_SL1500_.jpg That's a cool little device. From what I can see, it appears that it connects to the BNC channel on the scope and converts the leads into what you'd find on a DMM. The probes that came with the scope have x10 switches on them, but apparently the problem is not a voltage issue but a ground issue? I didn't have any issues last weekend testing all sorts of VAC sources from generators to inverters to wall power with nothing blowing up that I could tell, but I certainly don't want any trouble in the future. |
|
|
|
Posted: 7/9/2021 2:50:47 PM EDT
[#24]
OP, this video is a little long, but explains very well why hooking a scope directly to mains voltages is dangerous for you and the scope.
 EEVblog #279 - How NOT To Blow Up Your Oscilloscope! The video has diagrams starting at 5:00 |
|
|
|
Posted: 7/10/2021 10:11:48 AM EDT
[#25]
The scope came with two probes that allow switching to x10 attenuation. I bought a better probe with x100 attenuation. That lowers the voltage significantly. I was looking at a differential probe, but the price jumped up on me. I'm still trying to figure out all of the settings.
I did have a question about saving waveforms. It took forever to create a USB thumb drive format that the scope recognizes. I finally created one. When I downloaded some waveforms, I was expecting screen images. Instead, it looked like text files in .bin format. I'm guessing I need a proprietary program to interpret the data? I was reduced to snapping pics of the scope screen so I could post them. I was hoping for a more elegant solution. I can't find a setting to change the format of the data to .jpg or any other proper image file format. ETA: I found the setting that allows for saving in bitmap format. Let the good times roll. 
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
