RVelectricity: Get yer red hot projects right here, folks…

9

By Mike Sokol

Dear Readers,
Just a quick update on some of the cool projects I’m working on over the summer, a few of which I’ll be posting on my YouTube channel this weekend.

Click on for short video.

Here’s one I’m very proud of. I’ve been able to merge HRDL (my High Rate Data Logger) with Ecamm and YouTube, to produce real-time videos showing my previously captured current and voltage data. Yikes! Now you can see what I see inside of my head – which is a scary place indeed.

If you really want to understand the topics I’m writing about, and if a picture is worth a thousand words, a video is worth at least a thousand pictures. Click on the screen-shot graphic for a 4-minute video of me showing off my latest version of HRDL doing its thing with SoftStartRV starting current data. You’ll really want to watch this as it explains a highly complex topic in a very simple way.

Next up is a topic that’s getting a ton of interest over on the RVelectricity Facebook group, my Hughes Autoformer test. As  you may have heard by now, autotransformers of any kind in a campground (including the Hughes Autoformer) have been declared a code violation by the NEC as of 2020, and there was language beginning this autotransformer discussion as early as the 2014 code edition.

Hughes is defending their product saying it doesn’t produce any additional amperage load in a campground, while the NEC (National Electrical Code) states that autotransformers (including the Hughes Autoformer) add additional stress to a campground electrical grid that’s already strained to the breaking point.

So who’s right? Well, I really don’t know for sure even though I’ve been designing and installing buck & boost transformers (autotransformers) in industrial and production power grids for decades. But the one thing I do know how to do is run an experiment to prove it one way or another. So I just bought a 3,000 watt (25 amp) VARIAC® variable transformer (that’s bigger than my head) that can adjust the incoming voltage to any value I like between 0 and 140 volts. This will allow me to first gather baseline amp/volt relationship data on a Dometic 15kBTU air conditioner over a range of 120 volts down to maybe 95 volts. Then I’ll put the Hughes Autoformer in the circuit and log the same amp/volt data for comparison. By crunching the numbers I should be able to determine if the Hughes Autoformer is “robbing” power from other campsites (as proposed by the NEC) or saving overall power by reducing compressor amperage increases due to low pedestal voltage (as proposed by Hughes).

But there’s more…. In order to more closely simulate typical mixed RV loads I also need to add in a PWM power supply and an electric water heater element that both respond to low voltage differently than an air conditioner compressor. So I’ll also include a Progressive Dynamics load center with a converter/charger in the mix, along with a 1,500-watt resistive load bank to simulate an electric water heater element. For monitoring, I’ll then use HRDL+ (my new version that does both voltage and current monitoring simultaneously) to closely monitor any power factor or sine wave harmonic changes going on in the system that could contribute to campground grid loading and neutral overload from harmonically generated Triplen currents, but which may not show up with traditional meters. In short, I’m looking for everything possible, even things I don’t think will happen. Some fun, eh?

Finally, just for grins, this week I kludged together a quick experiment to see how much voltage was needed on an ground wire to trigger a Surge Guard due to an “open” ground. The quick answer was 30 volts AC, but I’m rebuilding this quickie test bench I threw together in 15 minutes to a fully monitored study that’s able to document the data on 30- and 50-amp versions of Progressive EMS, Camco, Hughes Power Watchdog and the Southwire Surge Guard advanced protectors. Yes, I have all of them…

Now, just as Frankenstein’s monster took some time to build, none of these experiments will be done in a week. But I fully expect to have the basic data captured by the end of August and sent to some of my colleagues for peer review and confirmation within a few weeks after that.

I know this all sounds like a super complicated mess, and indeed it is. But I’m hoping my videos and straightforward discussions of my findings can help you make better buying decisions that will improve your RV experience.

Yup, it’s gonna be a hot time in the old lab this summer.

Let’s play safe out there….

Mike Sokol is an electrical and professional sound expert with 50+ years in the industry. His excellent book RV Electrical Safety is available at Amazon.com. For more info on Mike’s qualifications as an electrical expert, click here.

For information on how to support RVelectricity and No~Shock~Zone articles, seminars and videos, please click the I Like Mike Campaign.

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Wolfe
3 months ago

Can you zoom in on the softstart graphs? I’m curious what it’s really doing while throttling the amperages — I’m guessing a high frequency PWM like a cheap motor speed controller. IF that’s true, it seems like an analog-feedback softstart could be made for $5 in parts — but it can’t be that simple, right?

I’d assemble my idea and test it myself, but I don’t know enough about the compressor’s response to my tampering — not affording a $300 softstart indicates not affording blowing up my own $1000 AC during testing… 😀

Sink Jaxon
3 months ago

“campground grid loading and neutral overload from harmonically generated triplen currents”
C’mon…really Mike???

Mike Sokol
3 months ago
Reply to  Sink Jaxon

Yes, really. Triplen currents build up the neutral wires in 3-phase WYE service panels that have loads which include a lot of harmonics, such as all RV converters and battery chargers. Due to the 120 degree phase angle, these 3rd, 5th and 7th (odd order) harmonic currents are additive on the neutral, not subtractive. This forces the Campground neutral wires to carry up to 150% of their calculated current, causing them to burn up. Since campgrounds are now allowed to wire pedestals directly with 3-phase 120/208-volt power, I’m predicting a lot of bad outcomes.

Drew
3 months ago

As I’ve said- I can’t wait for your Autoformer evaluations!

Thanks

DAVE TELENKO
3 months ago

Hi Mike, say ya know I bet we had one of those Autotransformers way back in the ’50 when I was about 8 years old I remember watching Jackie Gleason & the little TV’s picture would like dim to nothing & just disappear altogether. My Father bought this “thing” & hooked it up to the TV & we never had the issue again, especially Sunday morning comic hour! So now after reading what your saying how the Autotransformer works, the “thing” my Dad hooked up might have been one similar to todays version, but way more advanced!. Hey Mike we’re about the same age, did you have problems like that. I kinda remember that all our neighbors has voltage issues in Connecticut way out in the woods!
Looking forward to all your test & experiments, seems like your having a fun time.
Snoopy

Mike Sokol
3 months ago
Reply to  DAVE TELENKO

Probably so. I remember them from back in the 1960’s as well.

Don
3 months ago

Love it! You are my hero, Mike. Keep up the great work…

Mike Sokol
3 months ago
Reply to  Don

Thanks… I’m just a mad scientist with a lab full of dangerous gear. What can possibly go wrong?