LOW VOLTAGE WARNING

[187]

Last night before I started to roast I noticed that my Kill-A-Watt was showing 117.8V. This is on a very short run of #10 wire direct to the Behmor 1600.This line normally shows 122.6V. I called the electric company this morning and as I suspect the answer was "It's summertime" So all of you that think you have adequate power may all of a sudden have stalled roasts. I see a variac in my future.

[peter]

It would be interesting to do a actual bean temp vs. line voltage comparison, to see if a few volts translates into huge temp swings.

[187]

I don't know that anyone has addressed the V vs temp issue but my guess last night was to roast 12ozs instead of 16ozs using the 1 pound  P1 setting and I used the full time and only opened the door twice to stretch the 1C to 2C time. 

[187]

After the power company told me its summertime they must have had a change of heart and checked to see if there was a problem. Tonights roast gave me the following numbers 127.6V before I started and 124.4V under load. This voltage allowed me to draw 1711Watts under full load with the light on and 643W with only the afterburner and light on. Cooling drew 663W with the light on. At this level the small grid basket didn't make any difference. Anybody think this voltage is going to cause premature failure of anything, especially the motor?

[kwksilver]

Time of day plays a huge role in what you have available. Electricty on the scale of power companies cannot be stored, powerplants have limtied capacities of production. that is why the electricity market is a real time commodity game.
relatives in germany trade electricity for Eon. (I don't speak with him much, but he explained this to me once.)
Large manufacturing operations buy contingents of electricity in futures and those contingents are time specific. (at least in europe)
So apart from running manufacturing plants 24/7 for machinery cost efficiency production cycles alter.
Smelting on induction ovens is preferentially done at night when the electricity batches are cheaper.

(porsche does final assembly of the cayenne in leipzig because the shared platform comes from eastern europe, they bought that electricity in such batches. The corporate event on test track had they explaining this to us no-nothings. The timing of manufacturing processes that is.)

Knowing this I can imagine that you might see better line voltage at night? The voltage you see is not directly related to the output of a powerplant, but certainly is related to how much they are giving that grid sector.
Can your module plot historic voltage trends over a day? That would be extremely fun to see.

[Chris]

On a hot day when everyone is running their AC, my voltage during the day can be as low as 108VAC.  In the Fall, at night say when there is very little demand for electricity, it can be 124VAC.

A Variac helps you get a handle on this problem, as long as you get the 15A or 20A version (don't try to be cheap by putting a 20A fuse in the 5A Variac).  Sometimes it works, and sometimes you end up spending $$$ in fuses.

Any electric home roaster needs a Variac to get repeatable results IMO, regardless of what the manufacturers say.

[peter]

I should start playing w/ my Kill-A-Watt some more and plotting line voltage changes.

But I've never noticed a change in roasting times/temps, and maybe the fluctuation is more damaging to roasters that are more automated and less manual.  With my SC/TO's, and their accurate bean mass thermometers, I believe I can modulate heat and adjust for changes. 

Again, I'd need to see a measurement to see what the proportional difference is between line voltage and heat output.  Having a variac would make that experiment a lot easier.

[Ascholten]

The cooling is going to draw that kind of wattage because the 'smoke eliminator' element is burning away too to kill the smoke coming out.  otherwise its just the fan and motor running.

I work for a power plant and can tell you that voltages can vary significantly from time of day, temperature, and even in your building depending on what you have on.

I can be supplying 125 volts to your weatherhead, but if your A/C is running, you got the coffee thing cooking, possibly cooking dinner, and maybe even the water heater and washer / dryer... guess what, your voltage house wide is going to be quite low.  Nature of the beast there.

The age of the wiring in your house plays a big part, if you have aluminum wire plays a huge and most the times dangerous part....

Also, you plug the thing into a plug which is basically two pieces of brass that are springy together, so it's a pressure contact point, not really a hard contact, like bolted on or wire nutted or something difinitively making good solid contact.  Over time that plug can corrode, or the springiness gets weak and the connection is not very good, its loose,  voltage loss will happen there....  The kill a watt's  I have one for a certain type of..... cooker i use, and the plugs in them are not the very best either,  I burnt up more than one kill a watt on a mere thousand watts running through it for a few hours because of the loose springy plug thing.  yep voltage loss there, almost 3 volts.

Yes the variac can correct the voltage at the cooker but it does not correct the problem... you get the higher voltage at the cost of extra amps... if your circuit is overloaded, or you have loose contacts causing poor connection and HEAT at that spot, pulling more amps through it is only going to make that problem worse.   Before you go this route, please take a look and see if you can see what is causing the low voltage first, and be sure it's not a fault that could potentially turn into a fire.

Aaron

[kwksilver]

thats why we need to leave the dark ages of 110V. 220V is ten times better in every way 110V is just pathetic.

But I don't think that will ever happen.

[J.Jirehs Roaster]

thats why we need to leave the dark ages of 110V. 220V is ten times better in every way 110V is just pathetic.

But I don't think that will ever happen.

How true is this? I have been reading all over the net about coffee roasting and voltage issues and It has had me thinking
(A) If I get or make a construction site 220v to 110v break out box and plug it in to my 60A 220v outlet in the garage then I should have a very stable electrical source (at least as stable as Ascholten or his local counterpart can provide at the weather head)

(B) If I get the 220v Behmor roaster when it comes out and plug it into a 220v outlet then that too should beas stable as it gets?!?!

[kwksilver]

a 220V power source (a true one), has the capability to deliver more energy than either a 15 ampere or 20A 110V power source. That is about as certain as the fact that displacement in a combustion engine is an irreplacable physical entity.
VIR, ohms law and that.
If energy is what you are after a greater voltage to start with is a deeper breath. That cannot be replaced.
I am not a pro at roasting. Many here know a hell of a lot more on that than me. I think once you get into the bigger league's of roasting you will quickly be able to outdo any electrical source even something like 14-50 or 10-50 will be done around there. That is about the most you get as residential lines.
In commercial you can have IEC lines up to 900 AMP, but then your running a induction smelting ove or a maxipress or something?
I am sure there are many reasons why gas is the preferred energy source on larger scales, but I would not doubt that economcis is one of them.
I run my espresso on 220V and I have to say the difference is night and day. It was a pain in the bottoms to get there, but I do not revert voluntarily.

[cfsheridan]

I am sure there are many reasons why gas is the preferred energy source on larger scales, but I would not doubt that economcis is one of them.

That's one of the reasons.  Generation of electrical power from fossil fuels is roughly 25-40% efficient (and I am being generous); that is, only 25-40% of the heat energy generated by the fuel is converted into electrical energy.  That's not even counting transmission losses.  Taking electricity and turning it back into heat is economically silly.

Also, gas-fired stoves and roasters allow for more precise control of the applied heat--when the gas is off, there's no more heat addition (though there may continue to be heat added due to the heat in the drum).

[J.Jirehs Roaster]

I was just talking about the air popper or the eventual ST/CO

I can't imagine using anything but gas for a roaster bigger than 5lbs... I have a gas stove in my kitchen because the heat response quicker than electric, I suspect that is true in the roasting drum.

[kwksilver]

Yeah, your above explanations regarding gas make a lot of sense to me. I also subscribe to gas stoves. That brigns me toa  question. I am under the impression that sometimes the residential gas pressure in the U.S. has been sso low for me that the gas stove was a joke (glorified camping stove). This happened to me in my last kitchen. So instead of the "chef d cuisine" bang boom bang experience I had the "wait for it" experience on that one. Are there tiered gas line levels for sfety? Should one assume that was the stove or maybe simply a girlish line?

Regards,
           Felix

[peter]

Another thought occurs to me with regard to electric roasters; if a roaster has enough 'head-room' and can easily attain more than adequate heat, then voltage drops may be a non-issue. 

I'm just thinking out loud, as my SC/TO's haven't given me any apparent slowness or lack of response in the 3? years I've used them.  Perhaps roasters like the Behmor that have programmed temp/time don't/can't compensate for voltage drops, and don't have the 'head-room' either.

If a heating element has the ability to get the beans to say 475?, then if a voltage drop limits its potential to say 450?, it's no big deal.  But if a heating element can only get beans to 450?, then it may be in trouble when power is lessened.

Thoughts of an unlearned man, but it seems to make sense.