low voltage/roast stall

[JamesG]

This is more just for noting really, but I'm in Europe, and every now and then I get a low voltage warning (typically about 218-219V). This hasn't previously caused a problem, but earlier in the week I have a roast stall at about 220 degrees. It stayed hovering there for around 3 minutes before I aborted. I'll be more careful in future about not roasting when the voltage is low. (I suspect the voltage is off when our hot water heatpump is working overdrive).

[kaffelogic]

James, we are aware of this issue in Europe. The Nano 7 series B are designed for 230-240V and as the voltage drops the threshold is about 220V for successful roasting as you have found. This is perhaps not so much an issue for Nordic style roasting which finishes at 220 deg C, but there is always going to be a risk that your roast will stall if supply voltage is below 225V depending on ambient temperature.

To improve reliability you can do the following:

• Reduce the batch size to 90-100g green beans.

• Modify the profile (create your own custom profile) to reduce fan speed to as low as 92% of the default speed.

• Roast in a room where the air temperature is at least 18 deg C, using an extractor fan if this requires windows to be closed.

You need to ensure that the beans are still circulating adequately, otherwise you will get uneven roasting with a number of burnt beans in every batch. If that happens you know you have taken the fan speed too low.

With these changes you should be able to get reliable results with supply voltages as low as 217V.

We have a new heating element in development which is designed for typical European supply voltages. Once this is available it will be possible to upgrade your Nano 7.

[Angela]

I read something about European efforts of harmonization of power supplies across the European Union the other day. Lots of mainland Europe uses 220V whilst we in the UK use 240V.

Eurocrats decided to harmonize at a nominal 230V; that way no change, for anyone, would be required because all supplies would be in the margin for error of 10%. A wonderful fudge!

[JamesG]

To improve reliability you can do the following:

• Reduce the batch size to 90-100g green beans.

• Modify the profile (create your own custom profile) to reduce fan speed to as low as 92% of the default speed.

• Roast in a room where the air temperature is at least 18 deg C, using an extractor fan if this requires windows to be closed.

Thanks, that's really helpful. It's usually 22-23 ambient when I roast, so that is OK, and this is the first time in ~40 roasts that there has been a problem. I haven't successfully been logging, but having finally done my firmware upgrade yesterday, will target that next. Cheers!

[JamesG]

I read something about European efforts of harmonization of power supplies across the European Union the other day. Lots of mainland Europe uses 220V whilst we in the UK use 240V.

So Ireland is actually part of Europe then, even with the cable interconnect!!

[Angela]

So Ireland is actually part of Europe then

Let me reply in the vernacular; if I were you I wouldn't start from here!

[kaffelogic]

As far as I can make out (correct me if I am wrong) Ireland has a system that, like UK, historically was 240v. If that is right then there should be no issue for you, except on a bad day when supply drops below 225v. Other parts of Europe were historically 220v and that's where the problems start as they are routinely supplied with supply below 220v. Both the historically 240v and historically 220v supplies fit within the 230v specification, but deliver different typical supply voltages.

[JamesG]

Apparently 230V is their current target:

ESB Networks delivers electricity in a voltage range of 207 Volts to 253 Volts. This is in accordance with European Standard EN50160.

https://www.esbnetworks.ie/existing-con ... age-issues

I saw 211V the other day reported by the roaster.
Here are two recent roasts. 0003 went perfectly, but 0008 was the second in a couple of days where I have manually shut it down after I noticed the temperature starting to drop

roast0008.png (36.8 KiB) Viewed 6370 times

[JamesG]

I've created a profile called "euro ninja" with a slightly reduced fan speed, so will see how I get on!

[kaffelogic]

You can keep an eye on the supply voltage by pressing ☰ (info) until you see 'Technical information' then press ▶ until you see the supply voltage displayed. This will help you get an idea of how variable your supply is. From what you are reporting it is potentially all over the place.