I think I need to get a Variac

[EricBNC]

OK, I have a big box and three days off so now I need to figure out what is up with this new (to me) 22A variac. The big dial goes up to 100 - is this 100% or 140v? Do you put the kill-A-Watt into the variac plug and then plug the roaster into the kill-a-watt?

Thanks in advance for the help!

[mp]

OK, I have a big box and three days off so now I need to figure out what is up with this new (to me) 22A variac. The big dial goes up to 100 - is this 100% or 140v? Do you put the kill-A-Watt into the variac plug and then plug the roaster into the kill-a-watt?

Thanks in advance for the help!

I think that is right about the order of the Kill-a-Watt.

Can you post a picture of it?

 

[EricBNC]

The dial looks like this one - 0 to 100 and a black adjustment knob:

[mp]

Good picture!

So your output is 0-140 amps. Anyone can correct me but I believe if you put it to 100% you will get to 140 volts.

 

[EricBNC]

Thanks mp - if I give her all she's got will my popcorn popper ever be the same?

 

[mp]

Thanks mp - if I give her all she's got will my popcorn popper ever be the same?

 

I'm not going to answer that. I will leave it to someone who can give you a proper answer ... I don't know it.

 

[Aromajunkie]

According to your picture, the output of your variac is 0 to 140 volts, with a rating of 22 amps.

To answer the question "will my popper ever be the same?". Maybe not. The heat coil is designed for 120 volts. More voltage=more current. More current=more heat. Too much heat over time=burned out heat element.

If you bump the voltage to 140V, your 1500 watt rated popper is running at a little over 2000 watts.

Additionally, the variac increases output voltage at the expense of increased input current. At a 1:1 ratio (120V in, 120V out), your popper draws about 12.5 amps. When you crank the variac up to 140V, the input current (from the wall outlet) increases significantly and could approach your rating of 22 amps, increasing the risk of damaging the variac. By putting your Kill-a-Watt on the upstream side of the variac (at the wall outlet), you will see this.

Clear as mud? 

[BoldJava]

...
Clear as mud? 

I thought it was very clear, thanks.  When I use my Gene on the variac, I rarely run it past 121v.  I have been on this side of caution, making sure I don't fry the software within the Gene's components.  Figured there was some threshold to "problems ahead," and don't need more volts.  Once I hit a consistent 119-121V, I have all I need.

[rgrosz78]

Thanks mp - if I give her all she's got will my popcorn popper ever be the same?

I'm not going to answer that. I will leave it to someone who can give you a proper answer ... I don't know it.

You would NEVER want to max out the voltage provided via the variac.

I adjust my Variac to produce 115 volts before I turn on my Hottop. When it starts heating, the voltage drops about 5 more volts. Then I slowly dial up the variac to give about 120 volts to the Hottop.

In the later stages of the roast, I reduce the heat level on the Hottop. Each time I do that, I need to look at the Kill-a-watt display. I have to back off the variac so the voltage does not exceed 121.

</never mind>DOH!! You have a popcorn popper. Did not realize that you were using the variac to SLOW DOWN the roast. You are using the variac in the opposite way of most Hottop owners - which is to speed up the roast.<never mind/>

[rarebear]

Hook it up it like this, you'll have a digital read out of voltage output..
Or read the tiny analog meter

[ecc]

OK, I'm sure this is overkill, and anyone who understands these things will think I am being ... well afraid.  But here goes anyway.

1. Variacs have a serious safety issue of not being overload protected on the output side.

2. If/when variacs fail, it can be a very thermal event.  Like burn your wood deck and siding kinda event.

Number 1 means no short protection, no ground fault protection, no zap pop whoops gotta flip the breaker.  In outside, possibly damp conditions this means stuff should probably be a little off the ground and away from things that could drip on it, catch fire, etc.

Number 2 means you should have a way to get it well away from your expensive house/deck safely without having to reach over it to unplug it.

Overloading equipment voltage can lead to failure of any electronics in the path, as well as possible failures and even shorts on heaters and motors that aren't rated for it.  Setting it when the line is low, then having an oven inside the house kick off and send the voltage up 10% (to 132) might not be something you are comfortable with on a hand-held heatgun, for example.

Only you

can keep the fire dept from helping with your hobby.

[BoldJava]

I think you caution is wise. It's easy to become complacent when non-events lull our awareness of both electrical events and thermal catastrophes from small briquettes sitting in our coffee roasters.

[mp]

I think you caution is wise. It's easy to become complacent when non-events lull our awareness of both electrical events and thermal catastrophes from small briquettes sitting in our coffee roasters.

+1

It is wise to err to the side of caution than face the consequences on the other side.

[EricBNC]

So I went ahead and used it anyway. 1st roast was nice and even  - maybe I was too cautious with the 2nd small batch and got an uneven 8 min roast to 1st at 97v according to the KAW. more to come...

[mp]

Ok ... after a 13 day wait I've finally got my Kill-A-Watt. I don't know too much about this stuff but the KAW works like a champ and is very easy to use.

I took a couple of readings of my upstairs outlets and it read 121.3 volts.

More importantly I took the reading of the power-bar where I plug my roaster into and it also read 121.3 volts.

I'm now ready for the next step. How is it that I should proceed?