# Powering coffee machine



## FHustle (Jul 24, 2017)

Hi guys, I have a Coffee machine for my food van which is 4700watts.. I purchased a 5500watt generator to power it and when it gets up to temp the generator starts revving up and down like its about to cut out, however the circuit breaker doesnt cut out like it would normally if I overload the generator with other appliances. The coffee machine did originally came with a 20amp plug but i replaced it with a 15amp plug in order to fit into the generator and this is the only alteration that has been made. I have asked local electricians and engine guys and have received blank stares and no answers. Im a single dad struggling with a new business and am extremely limited in regards to cash after spending profits to buy coffee and generator so am in need of some quality advice  thanks in advance.


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## motormonkey (Jul 10, 2016)

Things aren't making sense.

240 vac times 15 amps equals 3600 watts. 240 vac times 20 amps equals 4800 watts. If a 15 amp outlet is the only outlet on that generator, are you sure it's rated for 5500 watts? (Maybe peak, but somewhat less continuous?) What kind of generator? BTW, for safety, you _really_ need a 20 amp plug/socket for that load.

You say that, "...when it gets up to temp the generator starts revving up and down like its about to cut out..." One has to assume that when the coffee machine gets up to temp, the temperature regulation circuitry of the coffee machine cuts most or all of the power to the heating elements, removing almost all of the load to the generator. Does the generator act this way with no load?

Perhaps the heating elements in the coffee machine are controlled by a triac circuit of some kind, and this is disrupting the generator's voltage and speed regulation circuitry. What kind of coffee machine? 

Too many unanswered questions.


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## exmar (Jun 29, 2015)

Initially, the coffee machine is presumably pulling the entire 4700W and the genset is happily powering it? That would be a steady state load and everything is working as it should. From my very little knowledge of coffee makers, I agree with MM comments that after brewing, electrical load should be significantly reduced to just keep hot as opposed to brew. Could the coffee machine achieve keep hot by cycling all the heating element on and off which results in a large power variation and the genset is struggling to compensate. e.g. like plugging and unplugging it when it's in brew? Maybe the issue is in the coffee machine and not the genset. I'd chat with the manufacturer and see how it achieves keep hot as opposed to brew.


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## FHustle (Jul 24, 2017)

The Generator is a MGS 5500E rated 5000 continuous.. The Generator does not rev up and down when i load it with other appliances. It cuts out like normal if it is overloaded. I too would also expect the load to drop once the coffee machine gets up to temp however, thats when the revving starts. The coffee machine is a NUOVA SIMONELLI.. 2 group, DIGIT 50 Hz, 220-230V, 4700 W, max pressure 0.18MPa max operating pressure 0.165MPa. 

Initially the machine is pulling the entire 4700W no worries.

I currently have the coffee machine hooked up to the house through a 10Amp plug and its working fine???

As I am limited with funds I am unsure whether I need to investigate purchasing a new and bigger geny or a new coffee machine that requires less power. Maybe I will have this problem with any geny that only provides 15Amp as this coffee machine is 18Amp?


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## Osviur (Sep 7, 2015)

Hi FHustle,

I have checked some features of your coffee machine, it is a computer controlled machine, with a touch screen panel, optional USB connected interface for external computer....and it makes coffee too!!

Temperature in the main boiler (14 Lt),is controlled by a electronic thermostat, as said MM, and the same may be for each of the individual boilers (1 Lt).

These devices are very sensitive to the electrical supply "quality". It means that the AC wave form must be a quasi perfect sinusoidal curve. The normal requirement for electronic devices is a maximum deviation from this curve of about 5%. This deviation is known in technical terms as Harmonic Distortion and the sum of all of them is the Total Harmonic Distortion (THD). This THD is a parameter in the generators characteristics that must be taken in consideration when electronic devices are to be fed from these power sources instead of the grid.

Ask your generator supplier for the THD , normally portable generators are in the 10 to 25 % with the exception of the inverter type (2-3 %). Anyway it is very possible that, inclusive working properly, the control system is on a on-off basis. To be sure you may usa a clamp ammeter and , using power from the grid, see if reaching the operational temperature,, the meter starts to increase and decrease the readings. The grid will not fluctuate as the genset does.

I hope this helps. Good luck 

Regards

PS: I found the electric diagram. The on-off system is controlled by a thermostat and a relay with cooper contacts, not electronic (Triac)Here is the diag. :

https://www.coffeeitalia.co.uk/pdf/download-nuova-simonelli-aurelia-ii-digit-electrical-plan.pdf
.


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## FHustle (Jul 24, 2017)

Hi Osviur,

All that and it makes Coffee too! haha.
That all makes sense however, I brought the Generator second hand from a guy that used it once then wound up his business and I am having trouble finding any info on the generator. 
After testing the Coffee machine and geny today it seems to be affected by the M-bar which I believe is a pressure rating for the steam? 
I start the Geny and Coffee machine and all is fine. The M-bar pressure is supposed to reach 1.20 and as it gets to around 1.10 it starts to rev up and down. I back the pressure down to 1.10 and it continues to rev once it arrives at that temp. I back it off to .80 and still it revs up and down. I then take it all the way down as far as it goes to .50 and it still revs up and down. It has no option to turn off steam that i can find. I turn the machine off, let it cool down and tun it back on while its set at the lowest M-bar setting of .50 and again it works fine initially until the M-bar pressure gets up to around .40. So it seems the generator is struggling to keep the M-bar at its temp. If I could turn of the steam I could froth my milk with a separate unit but alas I can find no way of doing so. Im a little lost in regards to what to do next? Get a bigger geny or a smaller non computerised coffee machine?


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## Osviur (Sep 7, 2015)

Hi,

I think that the problem is with the boiler thermostat. It maintains the proper temperature connecting and disconnecting the heating element which is the most important load for the genset. Loading and unloading the generator makes it (in theory) increase and decrease the torque applied by the engine to the generator shaft, maintaining constant RPM's.

It is different to rev up and down from change only the engine sound with constant RPM's. The governor is the mechanism that maintains the RPM's very near to 3600. Any deviation from this value (3500-3700) is a governor failure, unless the load be higher the gen capacity. This behavior is normal in a small gen . A large generator is very much stable in revs (1-2%).

In a small generator the governor may consist only in a plate spring loaded, opposed to the flow of air sent from the centrifugal fan and adjustable with a screw, or a more elaborated internal centrifugal mechanism. Both of them act over the carburetor shaft turning it more or less in accordance with the increase or decrease of the load.

To adjust the governor it is necessary to use a frequency meter or a tachometer. For 60 Hertz the engine must be turning at 60 RPSecond or 3600 RPM. For 50 Hz, 3000 RPM. To check the speed with a multi meter check the output voltage, then change the function to frequency, read and adjust properly with and without the load., 

Regards


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## thehandyman1957 (Feb 11, 2017)

So is it a 50 Hz coffee machine or 60 Hz? You state that it's a 50 Hz, is that a typo? If your trying to run a 50Hz machine on a 60hz generator I'm sure that's going to cause some issues.


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## Osviur (Sep 7, 2015)

Looking at the wiring diagram, it is possible to see the water pump as the only device that may be affected by the frequency difference. It would supply water faster at 60 Hz. But if it is working properly with power coming from the grid, the same would be with the generator, if this genny is OK, unless another welcomed opinion. I assume that the DC power supply is a Hi freq. switched type 100-240 V 50- 60 Hz.


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