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Bill,

Listening to this a few months late but thought I'd ask a question anyway.

You mentioned that aircraft and automobile structures aren't truly grounded (aircraft chassis are usually connected to earth during ground maintenance, autos aren't).

With the proliferation of 12 VDC-to-115 VAC inverters, some of them built-in to new SUVs, has safety become a concern because of possible high voltage differences in potential between the auto's chassis and earth?

Thanks,

Jeff

 

Iron

Lokking Forward to the next one

This lecture was action packed

Lots of informative things to think about

Thanks Jennifer, Thanks Bill

High/Low side sensing goes to V(+) or V(-)

Ground is ground =>earth

I use both in my designs

Iron

high/low side - depends where the load is placed

Iron

gnd is something very simple for someone who know how to use it (all types), and complicated for others -:)

Iron

Thanks Bill. Excellent presentation

Iron

I'm familiar with high side and low side sensing

Iron

Looking forward for tomorrow's lecture...

Iron

same here... not a single cetrificate since January...

Iron

same here, never got anything yet.

Iron

thank you checkman.

Time to earn my keep. see all tomorrow.

Iron

ok, will look into both, thanks

Iron

@cmeadows6959, checkman, I was wondering about that too. I haven't received any of the promissed certificates since attending back in January.

Iron

@cmeadows6959-Please let me look into this for you

Iron

I have been  wondering how  and when Do I Graduate? I have benn enrolled since Jan (session one and two)with passable grades.  Do we really get a certificate?

 

ok, thanks Bill! bye all...

Iron

OK, that's it until tomorrow. Thanks to all for attending and your questions/answers.

Blogger

Jojo--no, IMO, your problem is not the cap value, there is a problem elsewhere. Even huge caps could only supply 2A for a short while. Something somewehere, not the cap, is sourcing actual current.

Blogger

Listening to the recorded session...

Iron

Oops... late for the live session again...

Iron

OK, we're past the mid-week hump, day #4 is tomorrow. Signing off now, as we used to say in radio land.

Blogger

@bicyclebill: The current is a steady state. The configuration is as follows: 115VAC to EMI line filter to switch to system entry point. I tend to agree with the effect of caps in the line filter. should I get a line filter with lower cap value?

Iron

We're coming up on 3:00 ET, so this session is coming to a close soon. Thanks to all. See ya' tomorrow, hopefully.

Blogger

Jojo--if it not a miswired outlet or switch (or defective switch--could be) then probe with a voltmeter looking for potential difference (aka voltage)--since that is what drives the current you are seeing.

Blogger

jojo--wow, that's nasty. You'll have go go through things connector, wire, and chassis inch by inch, look for intentionmal or unintentional contact points. That's a lot of current to be leaking through. Whatever you do, use an isolated (battery powered) meter--not a plug-in.

Blogger

Mis-wired outlet?? The power switch is turning off the neutral....

Iron

Not really, it is always there when the power is turned off which presents a safety hazard.

Iron

jojo--current can't come from nowhere, of course. But first--is that 2A steady state or a transient? If a transient, it may be from caps in the line filter. In general, caps anywhere in a system are a potential source of unexpected current flow (and voltage sparks) even after primary power is shut off. Old TVs for famous for this, with their high voltage supplies--you get get a lethal spark 30-60 minutes after shutting it off.

Blogger

@JoJo : Discharge of Stored Energy?

Iron

@bicyclebill: I have 115VAC supplying power to my system. This 115VAC is going through an EMI line filter prior to entering the system. When I turn off the 115VAC switch to my system I measure approximately 2A flowing in my ground wire. Can you please explain why I am measuring 2A flowing in my ground wire?

Iron

I can see why you'd put the instrumentation electronics behind an isolation transformer, but I guess I don't really see why you would need to isolate your shunt... I'm just trying to think of a scenerio.

Iron

Anyone else? I welcome your questions--and even if I don't have the answer, I suspect someone in our audience will.

Blogger

cmeadows6959: most test transducers are pretty stable-unless there are dramatic shifts in ambient temp, or their dissipation, or they have been overloaded. But if they are "moved" they may need recal due to ambient magnetic fields, for example.

Blogger

NSL22--if you have an isolation transformer, you'd usually place the shunt after it.

Blogger

How often should our test transducers be calibrated?

 

Ivek--sorry, that's outside the scope of time we had, except we will touch on it briefly on the last day. But vendors have lots of good detailed specs.

Blogger

Thanks Bill, great presentation!

Iron

so you place your shunt after a isolation transformer?

Iron

Are you planning on discussing isolation/common mode voltage ratings of certain devices/circuits?

NLS22--it depends--one side of a single-phase AC line is called common, usually also connected to earth ground. Three phase not so. But most AC line measurements use an isolated coil, so high/low side is not an issue. And it's safer, too.

Blogger

Check out our Model 2802 Power Analyzer, it has the ability to be connected to External Shunts, Rogowski Coils, Hall Effects or with use with our built in Shunts, we are used for Energy Star Compliance, IEC62301 and high power applications.

OK, thanks. For measuring AC, is there still such thing as High Side/Low Side reference?

Iron

NSL22--this is the Q&A--your questions and audience answers are welcome; I will also try to answer.

 

Blogger

Energiman--you need a scope or equivalent to see what you have, and there are power meters for non-sine rms situations. It depends on what you are trying to see: power factor, waveform shape, transients, or just power used.

Blogger

is this where you're having the Q&A?

Iron

I'm using Rogowski & Dent module to measure mains kW & am seeing 8% difference vs utility meter - why?

       Hydrogent- please give us a call at the factory and we will be happy to answer your questions. Christopher Dent, President DENT Instruments

Can I please have a T-shirt in XL  ?

Mr E: to verify isolation, I suggest two things: look at the drawings--assumng you have them, and measure with an ohmmeter, just to be extra sure (and be sure all power is off, first). You should see infinite resistance. If you don't--find out why--where is that current flowing? But also be sure nothing changes state when you turn power on (such as a relay) which chnages the isolation situation.

Blogger

Bill what considerations are needed if looking at a non-sinusoidal power signal e.g. Variable speed drives?

Iron

Great Presentation Bill, sorry that Mondays did not go through.

 

I want a T-shirt, please.

keep up the good work. Rodney Rutherford

Iron

Thanks...enjoyed presentation.

Iron

Thank you great series...back to work

 

Iron

tthanks bill. great prespective.

When lookinmg at Test Equipment verify if the unit is electrically isolated, for Sensors, we calibrate and or verfiy the Sensor with known currents flowing through them and can then characterize the performance with in our Power Analyzer.

Thanks Bill and Jenn.

Iron

Thanks! Excellent presentation & information.

Iron

Thank you Bill and Jeniffer

Iron

Jennifer, Is there a way to download the archived audio to listen off line?

Iron

Interesting session, thanks

Iron

@Bill & Jennifer- Thanks for the presentation!

Iron

Good seminar thanks.

Iron

Thanks Bill and Jennifer.

Iron

Are your CTs and VTs rated for custody transfer (ie accurate)?

Iron

I'm using Rogowski & Dent module to measure mains kW & am seeing 8% difference vs utility meter - why?

Iron

@bicyclebill: Is there a way to verify the electrically isolated interface before you connect to the unit under test?

Iron

Yes I am familar with high and low side sensing

 

Iron

What Bill calls "differential effect" sounds suspiciously like what some call "common mode rejection".

Iron

My audio was intermittent until I 'paused' the audio for 5 seconds.  Now I have a 5 sec buffer and have had no problems since.

Iron

Thanks Bill and Jen - got to go for now

See you tomorrow

Jarnail

Iron

back to the burnt scope clip!

Iron

I see what's going on here, it is being blocked but the notice is compessed small and was off the screen. When I clicked on it, it said content blocked. I guess I'll have to catch the rerun form home.

Silver

Hi all from California.

Iron

how is the wind in Miami  it is picking up in Daytona

Iron

The YouTube inbed is if you want to send a video.  Course is audio with powerpoint slides.

Iron

a smoking scope probe clip gets your attention and reminds that the scope is connected to earth ground.

Iron

lost audio again - refresh

Iron

Hi from Midland, late

Iron

mine is turned up and I installed latest flash palyer mon

Silver

audio is good. did you click on play button?

Iron

I think it is just audio

 

Iron

Access Denied

No audio and video. I would think our comany block all the YouTube video.

Iron

My audio is good....is it turned up on your computer?

 

Iron

High side is the point at a potential furtherest from ground in the system. Commonly the side not ground

Silver

I have no audio

 

Jarnail

Iron

I have no audio, maybe my co's blocking

Silver

Ground: safety - path for leakage & fault currents; signal - return path; RF - capacitive plane

Iron

1. A reference for all voltages in a system.

2. Hi Side = the side of a transformer with the highest voltage (usually the incoming). Lo Side = the side of a transformer with the lowest voltage.

3. No

Iron

ground is earth ground - not circuit common.

I'm familiar with difference between high side and low side sensing and control, we use the techniques in most of our embedded designs.

Iron

Ground is a point kept at (or close) to the potential of the actual earth

Silver

I can hear it this time!

Iron

Here we are again

Silver

it's about 75F in Detroit!

 

Iron

I'm ready to go!!!  Thanks for putting on these courses.

 

Iron

@wlasalle, yes, part of the small lakes here are already freezing over! It gets pretty cold overnight these last few days.

Iron

please tell us when to refresh to get audio

 

Iron

Are you serious danlafleur?

Iron

Hello from sunny, although snow-laden, Calgary Alberta Canada.

Bil I am looking forward to your presentation today

Jarnail

Iron

Hello from Daytona Beach.  Sunny and 84 Deg.

Iron

There is no audio icon / controls yet, that's it?

Iron

Hello from chilly Edmonton, AB. Not much snow yet, but some of the geese are already walking on the lake instead of swimming.

Iron

Good afternoon folks.

Iron

Hello from Melbourne Beach, FL

Iron

Hello from Austin, TX

Silver

Thanks for checking in...we'll be starting on the hour.--Bill Schweber

Blogger

Good Afternoon, Everyone

Iron

Hello from Huntsville, Al.

Iron

Hello from sunny (SE) Lake Simcoe, Ontario Canada

Iron

Hello from Dearborn, MI

Go Tigers!

Iron

Howdy from Fort Worth, TX

Iron

Good Morning/Afternoon from San Jose, CA

It's 48°F now with a High of 61°F Partly cloudy and clearing this afternoon.

No Rain on The World Series Game 1.

GO GIANTS!!!!

Iron

Hello from Baton Rouge

Iron

Good morning from San Diego, CA

Iron

Hello from Melville, NY

Iron
Good morning from Mesquite, NV.
Iron

Thank you for the classes. I wish Digikey / Design news does a class or two on stepper and dc motors and controls. Many people and I mentioned this pont here earlier. I hope they are trying to bring in some motor experts.

 

Iron

I just read your notes and hope to be online asap.

Keep up the good work.

Iron


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