Turbo oven, Powerstat fuse, and Poppery I (!)

[prof_stack]

A lot in that title, for sure.

Yesterday the 8 amp fuse blew in the Powerstat 116 while it was paired with the GG Turbo Oven (1475 watt) for the first time. The roast finished fine with the Turbo Oven and Stir Crazy and tasted great today. Its nice doing 250 or more grams at a time. Very evenly roasted beans with a smooth flavor compared to the poppers I've used for a couple years.

So today I went and found a replacement fuse while my wife was doing her usual weekend thrift store searches for this and that. She stumbled upon a Poppery unit and wasn't sure if that was the one I've mentioned for months to look for. A nearby Poppery II answered that question and the Poppery was waiting for me when I got home. What a heavyweight brute of a popper! 1500 watts! Now I see why it is the holy grail of poppers.

So I roasted 150g of Colombian beans with the Poppery I and Powerstat and it handled the mass with no problems. In 12 minutes the roast was 1 minute into a good 2nd crack when I stopped it. Nice bright aroma.

That and a great Spring motorcycle ride today in the PNW sun and it was a great day!

For you Poppery I experts:
- What is an optimal range of grams of beans to roast? The ambient temp today was 55F.
- Have you had any problems using a Variac or Powerstat with the 1500w unit?

One more:
- Any ideas why the fuse blew yesterday? I had the TO set to 500F and was using the Powerstat to try to control the temperature.

Thanks for any and all replies.

[farmroast]

Is your Powerstat rated for the amps of the turbo top? I think the tops use about 12-13 amps

['Q']

1475 Watts @ 120 Volts = 12.3 Amps ... or... @110 Volts = 13.4 Amps

I would expect it to blow if the TO was on full.

[another_jim]

For you Poppery I experts:
- What is an optimal range of grams of beans to roast? The ambient temp today was 55F.
- Have you had any problems using a Variac or Powerstat with the 1500w unit?

Around 150 grams for the unmodified fan. Use a step up transformer and dimmer on the motor only, and you can go to 250 grams. Just add beans until it's barely moving at the start. I find that loads exceeding 175 suffer in roast quality, even if one has hopped up the fan, since one either has to get too hot on supply air, or take too long to roast.

Your best bet is to split the fan and heat, and variac the heat. This is easy with a P1, since the 110V fan and heater have separate wires to a screw terminal; all you need to do is add a second plug. Variacs are rated in KVA (volts times amps) with the plate rating meant for continuous use with motors. Using it with a heater at double the rating for an hour, or triple for a half hour will keep you within the manufacturers specs providing you give it a few minutes rest to cool off afterwards. In other words, 500 KVA variac will do the job if you are running only the heat, and throttling it to keep your roasts around 10 minutes; a 1000KVA variac won't even breathe hard -- you will need to fuse it at 15 amps.

One more:
- Any ideas why the fuse blew yesterday? I had the TO set to 500F and was using the Powerstat to try to control the temperature.

Fuses operating close to their rated amperage can blow out of the blue, especially when there's any sort of motor involved. Find a slo-blo fuse to minimize this.

[prof_stack]

Thanks for the helpful answers, guys! Much appreciated.

Electricity 101 eluded me, and I forgot that Watts over Volts equal (more or less) Amps. The Powerstat is rated at 8 amps. I put a 10 amp fuse in its place and it did fine on the 12-minute Poppery I roast. But I take it that it really isn't wise to mess with a higher amp fuse. But I did get a slo-blow fuse in the assortment my step-dad gave me from his treasure trove of decades of machinist workings.

Good tip on the P1 separation of heat and motor. I will do that later but for now I'm going to work on getting the TO/SC roasting system under my belt. The three roasts so far have gotten progressively better each time.

[DigMe]

Around 150 grams for the unmodified fan.

This is exactly what I have concluded as well from my experiences/experiments. I typically use the SC/CO as well but the Poppery 1 is a great machine. Mine has been pulled from a table to the concrete and then chewed on at least twice by my dogs and functionally it hasn't blinked.

bc