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Thread: VFD install summaries
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4th September 2018, 10:21 AM #196
I am reminded that, before I knew about the ‘VFD option’, I went to an auction at the local Technical College who were closing down their cabinet making courses
A brand new, still on its pallet, 3 PHASE Sawstop table saw was sold for $500!
If I had known then about the option of VFD, I would have bought it because I would have rationalised that I had about $4000 to spend and still been ahead?
Where I envisage the single page document would be used is, when the Committee sit down and say “its going to cost $30,000 to connect 3 PH to the shed, what do we do, the listed options would include getting quotes for the installation of X number of VFDs?
I guess it’s the ‘pink Volkswagen syndrome’ where you never see a pink Volkswagen until you own one and then you see them everywhere, but I now notice lots of very cheap, excellent brand, 3 phase machinery available.a rock is an obsolete tool ......... until you don’t have a hammer!
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4th September 2018, 10:35 AM #197.
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At the other end of the $ scale it could be something like a shed already has 3P but the committee wants to locate a small 3P machine some distance away from the nearest 3P outlet but close to a 240V GPO. The cost of a sparky installing a new line and a 3P outlet is not cheap. If the machine's motor is readily convertible a $100 VFD could be a cheaper alternative.
It also may pay to point out things that are obvious to some of us like "will not work on SP machines unless motor is swapped for a 3P motor"
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4th September 2018, 11:16 AM #198GOLD MEMBER
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Or if they smoked a single phase motor and have a 3 ph motor already the VFD would be cheaper than getting a single phase motor to replace the duff one.
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25th April 2019, 07:37 AM #199Senior Member
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Any progress on the flier?
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25th April 2019, 09:05 AM #200.
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25th April 2019, 10:21 AM #201
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26th April 2019, 12:29 PM #202
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13th September 2019, 07:44 PM #203.
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Latest VFD install, not for workshop machinery but for my coffee machine!
The coffee machine is plumbed in with water direct from a water purification system, and waste goes directly down the drain.
The pump that was inside the machine was a vibratory pump that was pretty loud, (~85 dB) which made coffee making in social settings problematic.
The new setup uses a used 1/5th HP 1440 rpm 3P motor (Which I got for $30) coupled to a very rugged ~200 l/min stainless steel pump from a large multi-portafilter cafe style coffee machine (got the pump at cost through a friend).
The 200 L/min is definitely redundant I just wanted a rugged pump.
The VFD is a 1/2HP Telemechanique (obtained from free from Ericks2- thanks ) with no external stop/start or speed controls, so it has to be controlled remotely.
The new motor, pump and VFD sit on a cupboard shelf under the bench where the coffee machine is located and is powered through the coffee machine mains
A small micro controller hung on the side of the machine does the switching, sensing and reporting
The usual start/stop button on the machine controls the VFD which starts pump to push the water through the coffee (plus the pump auto starts and stops to maintain the water level in the boiler)
First thing I had to do was make up a coupler between the pump and motor.
The coupler is the two SS discs and the things in between.
Pumpscreen1.JPG
Below is a photo showing the motor, pump and VFD in the cupboard under the coffee machine.
The water comes into the cupboard from a water filtration system in the cupboard next door goes through a solenoid (S) and a Pressure reducing valve (PVR) then to the pump where the pressure is sensed by PS and fed up to the machine via the braided SS hose..
V is the VFD over the back.
CLoseup.JPG
Up at the machine the microcontroller is inside the plastic box hanging off the side of the machine.
Arduino1.JPG
Closer up the screen shows.
BT = Brew temp - 144 oC is meaningless - I did not have the temp sensor connected up at the time the photo was taken.
PP = Pump pressure in bar
ET = elapsed time - or "Shot clock" that tells you how long the pump has been running - max is 60s and then it turns off the pump.
MF = motor frequency - controllable manually by the coarse and fine pots on the RHS side of the box
PRESSDISPLAY.JPG
Pressure ranges start from the pressure of the Mains pressure reducing valve, ~4 bar, up to when the machine's over pressure valve kicks in (set at 13.5 bar)
This means if the coffee is coming out too fast you can slow the pump down air VV.
Supposed to get better coffee this way.
Lots of technical issues to sort as I wanted the original controls on the coffee machine to start and stop the VFD/pump. Also I didn't want multiple power switches (invariably I'd forget to switch one on/off) so everything is done through the machine. ie VFD/Microcontroller/machine all start via the machine.
LotS of prototyping outside with things connected to the garden hose - this enabled me to sort out electrical issues and leaks etc of which there were quite a few.
Prototyping.JPG
So far so good. - noise wise it's <55dB!, just need to fix the thermocouple.
Haven't had a chance to see if it affects the coffee yet.Last edited by BobL; 19th June 2020 at 10:22 AM.
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16th September 2019, 08:55 PM #204.
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The thermocouple turned out to be OK, what was not was the Electromagnetic Interference from the VFD.
The VFD was generating AC signals (whether the motor was running or not) all through the system and this was being picked up by the thermocouple lead and being fed to the thermocouple amplifier.
For the solution see Coffee machine experiments - Page 4
There's a simple $2 useful suggestion in that post as to how to reduce the AC noise from a VFD.
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