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Smart Meters
ChicagoJohn
I designed my newest hot air roaster around our service which was typically 124VAC without load and at the 20A outlet I'm using, under full load with the roaster, the voltage dropped to around 116VAC, probably due to the long run, over 90 ft. to the junction box. This gave me around 1870 watts of heating with the 7.2 ohm nichrome coils I'm using.

Then a couple of weeks ago, the electric company installed "smart meters", which I assumed meant they'd be able to retrieve usage data via the internet. About that time, maybe shortly thereafter, I noticed a drop in voltage during roasting. The line voltage without load of any kind on this circuit dropped from 124 down to 118. Under the full load of roasting, I am now getting 108VAC which translates into 1620 watts, a decrease of 13%, and I am now struggling to balance charge and blower speed to get up to temperature. Since this appears to be a permanent change, I've decided to try using a variac to try and boost voltage.

There doesn't appear to be any other assignable cause, but I also don't see why a smart meter could cause a voltage reduction. Does anyone have experience with smart meters and line voltage that would suggest this is something that would be expected? I would think the voltage to a house would be controlled by the local transformer.
So many beans; so little time....
 
jkoll42
Yeah, those smart meters are capable of regulating voltage. Assuming your name actually has you in Chicago that's one area I know (like PECO in philly where I'm at) that has voltage regulation ability. Here smart meter adoption is voluntary and the incentives were so lame I opted out. Here they can also throttle A/C operation during peak summer conditions if they want.

Variac is a good move.
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
ChicagoJohn
jkoll42 wrote:

Yeah, those smart meters are capable of regulating voltage. Assuming your name actually has you in Chicago that's one area I know (like PECO in philly where I'm at) that has voltage regulation ability. Here smart meter adoption is voluntary and the incentives were so lame I opted out. Here they can also throttle A/C operation during peak summer conditions if they want.

Variac is a good move.


Thanks, Jon. I decided to call Commonwealth Edison after I posted this today and they put in a request to check for low voltage. The guy was just here and I had a chance to talk to him. He got the same voltage I did. Here these smart meters are apparently being used in connection with "voltage optimization" wherein the utility manages their grid on the low side of average to reduce power consumption. He told me this would be the case during peak usage as you said such as A/C, but it's been running in the 40-50F range for quite some time here and that isn't a factor yet. This appears to be a general strategy they have implemented pretty much 24/7 all the time.

The smart meters provide data several times an hour to allow them to insure no remote legs on the grid get below the bottom, which I believe would be about 113VAC for lighting and still lower for power applications. So I'm glad to know it's just the new normal and not indicative of any problem condition. The variac I ordered should put me back up in wattage where I designed the system for, and maybe even improve on that a little.

Interesting that you live in Phila. I lived out Baltimore Pike in Clifton Hts a long time ago (when Frank Rizzo was mayor :) and then Regent Sq close to Drexel. I worked at DuPont on Grays Ferry Ave and then went to grad school full time at Temple. I lived in the area about seven years and really missed it a lot after I left. We now live about 50 miles west of downtown Chicago in a rural environment.

Anyway, thanks for the advice.
So many beans; so little time....
 
jkoll42
Nice - I was a kid in Jersey when Rizzo was around but he's certainly notorious. We were just at the Philly zoo for the first time in a decade or so and it's actually nice now. New parking garage so you don't have to walk by burned out rowhomes at the old main parking lot!

Your old DuPont land was purchased iirc by UPenn and was going to be turned into a research area for research of police k-9, dental stuff and something with fuel. Don't quote me on that.

I'm just outside of Philly, you're just outside of Chicago. Both good things - you know the OUTSIDE of part :) The time I've spent in Chicago has been airport and downtown for conventions and it was nice but man Chicago has some tough issues as does Philly.
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
ChicagoJohn
jkoll42 wrote:
Chicago has some tough issues as does Philly.


Very true.

Thanks for the update on 3500 Grays-Ferry Ave. When I was there, the lab and paint plant was next door to a slaughterhouse. On the whole, the new arrangement sounds like an improvement. :)
So many beans; so little time....
 
ChicagoJohn
Well, looks like the variac solves the problem. It'll take the open circuit voltage up to over 150, but setting it to 120 VAC at maximum heating during a roasting cycle is 130 open circuit -- the same 10VAC drop in the line I'd been seeing.

I was easily able to do 350 gm from a cold start and I'm thinking 450 - 500 gm should now be within range. But I'm going to sneak up on it.

Thanks, AllenB, for suggesting a variable boost transformer some time back. It wasn't necessary at first but is now that ComEd has decided to put in smart meters and implement a voltage optimization program. I was able to get the 20A variac for only $104 including shipping, and since I'll just be leaving the rotor set in one position, I'm hoping it'll last a while.

The profile for today's roast is shown in the attachment in case anyone's interested.
ChicagoJohn attached the following image:
run-with-variac.jpg

So many beans; so little time....
 
jkoll42
Great news! I had a chance to buy a used variac cheap years ago but didn't. I have no current use for it but still kicking myself in the shins because I'm sure at some point I'll wish I had it! Really happy for you that this fixed things up and you're back up roasting
-Jon
Honey badger 1k, Bunn LPG-2E, Technivorm, Cimbali Max Hybrid, Vibiemme Double Domo V3
 
ChicagoJohn
jkoll42 wrote:

Great news! I had a chance to buy a used variac cheap years ago but didn't. I have no current use for it but still kicking myself in the shins because I'm sure at some point I'll wish I had it! Really happy for you that this fixed things up and you're back up roasting


Thanks, Jon. If you're ever in need of one again, I got the 20A, 2KVA unit shown in this picture from circuitspecialists for $104 including shipping. I picked up a spare pair of brushes too just in case though I don't anticipate the need to change them. This thing will go up to 150+VAC open circuit with our line at 118, so I've got some headroom if ComEd starts to get more aggressive with their "voltage optimization" program this summer.
ChicagoJohn attached the following image:
variac-and-coffee-roaster.jpg

So many beans; so little time....
 
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