Help Getting Started with PID and Artisan - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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Jake_G
Team HB

Postby Jake_G » Mar 07, 2019, 11:02 pm

ontum wrote:Hello,

I would like to be able to vary the fan speed and drum speed of the roaster.

I've never used a a VFD before. Can I just install a VFD like this for each motor and hook them up to Artisan through the RS485 I will be running for the PIDs?

You cannot, as those drives output 3 phase AC.

You can use an SSVR (solid state voltage regulator) as some of the other roasters (North) do on their blowers with some success, but the drum is usually better handled by a DC motor and controller (cheaper but requires mounting a "different" motor footprint) or by switching to a 3 phase motor and VFD drive (more costly, but you can mount a direct-replacement for your motor).

You can try the SSVR approach on the drum, as well, but it's a less common solution and you'll run into problems if your motor uses a start capacitor with an inertia switch, as they dont like running below the the minimum speed that opens the start capacitor circuit. Fans are generally equipped with a start winding and a permanent capacitor, so they fare better with SSVR speed regulation. SSVRs can be had for relatively cheap. But they generate heat and need to be mounted accordingly (heat sink, good circulation, etc...) lest they burn up.

Cheers!

- Jake
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EddyQ

Postby EddyQ » Mar 07, 2019, 11:26 pm

ontum wrote:I've never used a a VFD before. Can I just install a VFD like this for each motor and hook them up to Artisan through the RS485 I will be running for the PIDs?


VFD's are fantastic because you can infinitely vary the motor speed over a wide range of RPMs without much if any loss of torque. However, your motors need to be 3-phase motors, which they are not. You will need new motors and if you go that route, it is best to get inverter ready 3-phase motors which are designed for the high current at low RPMs than you can get with VFDs.
VFD's also are designed for different sized motors. Good ones have an adjustment on max current so you can use them on rather small motors.

I replaced my North 1K fan with a 3-phase fan and got a VFD. It is great. Some day, I may connect it to Artisan through a modbus connection.

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Jake_G
Team HB

Postby Jake_G » Mar 08, 2019, 12:26 am

Eddy,

Is the VFD a notable improvement over the stock SSVR approach to modulating fan speed? I'm assuming the answer is "yes", but curious as to what's better about it. Repeatability? I'm also a huge fan of VFDs, but can't think of what the real benefit would be with something like a fan that doesn't need precise speed matching or anything like that. Your experience would be most helpful.

Thanks!

- Jake

EddyQ

Postby EddyQ » Mar 08, 2019, 6:08 pm

Jake_G wrote:Is the VFD a notable improvement over the stock SSVR approach to modulating fan speed? I'm assuming the answer is "yes", but curious as to what's better about it. Repeatability? I'm also a huge fan of VFDs, but can't think of what the real benefit would be with something like a fan that doesn't need precise speed matching or anything like that. Your experience would be most helpful.


My 2015 vintage MC North 1K had basically a lamp dimmer type fan control (likely a SSVR type). The full roast range of the fan knob settings was a fraction of the knob turn. So modulating airflow was rather tricky. But worst, the air was very inconsistent. I bought a Magnehelic to sense the actual air flow and it basically was up and down all over when roasting. This variation showed up on my input air probe (MET) as well (this variation is what prompted me to buy the Magnehelic). I could roast with it, but it required constant attention. If I turned to look at my laptop for 15sec, the MET may jumped 20 degrees when I look back. And occasionally, the fan would completely stop turning at lower settings. Very annoying.

With the vfd, I set the knob and airflow never changes (unless it is a windy day and I get some back pressure variation). I can easily sense when my system needs cleaning when my knob setting for a given pressure moves higher. I think all the newer MC roasters have a vfd fan.

ontum

Postby ontum » Mar 08, 2019, 8:36 pm

Great information.

I feel like the drum speed of the Toper is too low. The topper is set up with a motor -to- gear reducer -to- pulley/chain/pulley -to- drum shaft.
I would like to change a pulley or something to increase the speed. And then be able to slow down the drum speed from there, preferably with a VFD and three phase motor. Anyone have a good source for motors and drives?

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Whale

Postby Whale » Mar 09, 2019, 5:31 pm

ontum wrote:Great information.

I feel like the drum speed of the Toper is too low. The topper is set up with a motor -to- gear reducer -to- pulley/chain/pulley -to- drum shaft.
I would like to change a pulley or something to increase the speed. And then be able to slow down the drum speed from there, preferably with a VFD and three phase motor. Anyone have a good source for motors and drives?


I fully agree with this statement. I have increased the speed of mine by changing the gear ratio of the sprockets in the chain drive.

From another thread of a while back:

Whale wrote:The maximum drum speed is, in rotation per minute, (30/Pi)*(g/r)^1/2. Where g = gravitational acceleration (about 9.81 meter/sec), r = the radius of the drum in meter. This is the speed at which the beans are kept in contact with the drum (force of gravity = centrifugal force ).

There is a paper by Henry G. Schwartzberg, (http://www.nt.ntnu.no/users/skoge/prost...s/600b.pdf) (original link by Jim Schulman, thank you again) in which it is stated that optimal should be between 0.9 and 0.75 of that speed.
LMWDP #330

Be thankful for the small mercies in life.

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drgary
Team HB

Postby drgary » Mar 09, 2019, 6:27 pm

ontum wrote:Great information.

I feel like the drum speed of the Toper is too low. The topper is set up with a motor -to- gear reducer -to- pulley/chain/pulley -to- drum shaft.
I would like to change a pulley or something to increase the speed. And then be able to slow down the drum speed from there, preferably with a VFD and three phase motor. Anyone have a good source for motors and drives?


During one of the early Mill City videos, Dave Borton, aka Boldjava, said that he aims for the beans tumbling at about a 45° angle. This would provide some drum contact and would also have them aloft some of the time. This isn't nearly the precise measurement suggested by Whale, but it might be a good place to start. With a larger charge I increase drum speed to achieve that angle.
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

ontum

Postby ontum » Mar 11, 2019, 3:48 pm

I am no computer nerd, but I try. It took some doing, but I finally got both Delta DTA connected to artisan. I wasn't able to find detail or explanation to configure the Detla DTA with Artisan. I did find this post where someone had the same symptoms as I did. I set all the configurations in Artisan to match the defaults of the Delta DTA, but I got no communication with the Delta DTAs in Artican. In that post the OP tried to configure the Artisan serial port to match what was the default setting in the Delta DTA. I also tried this over and over with no luck.

Finally I configured both the Delta DTAs to that of the defaults of Artisan Serial Ports and BAM!, I was able to see temperature in Artisan for the first time and manipulate the SV through the RS485 connection. I don't have the outputs of the PIDs set up yet, but it was great to finally see that temperatures in Artisan.

ontum

Postby ontum » Mar 11, 2019, 3:56 pm

drgary wrote:During one of the early Mill City videos, Dave Borton, aka Boldjava, said that he aims for the beans tumbling at about a 45° angle. This would provide some drum contact and would also have them aloft some of the time. This isn't nearly the precise measurement suggested by Whale, but it might be a good place to start. With a larger charge I increase drum speed to achieve that angle.


In the Toper with 800g I don't even get enough rotation of the drum to catch beans with the trier until the beans are mostly through the drying stage. So I think increased speed and control would be a nice help of this roaster.

ontum

Postby ontum » Mar 11, 2019, 4:02 pm

I got Artisan up and going, but cannot figure out what is going on the the BT. The BT dipped down after the charge and never came up. The beans seemed to roast okay, but I don't know what is going on. The BT probe is a 3mm x 50mm RTD probe for the BT and the ET is 5mm. Do I have a bad probe??? Here is my first ever Artisan Roast.

FYI these numbers are in Celsius, even though there is an F

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