Three-Phase Power for Beginners

the business of coffee houses

Postby Daryn Berlin on Wed Oct 25, 2006 9:47 pm

My suggestion would be to call a licenced electrican with references. Give him your equipment list and specifications and ask him if they are compatable.

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Postby Lee Corrina Cano on Wed May 09, 2007 12:38 pm

Hi... It's like six months later and I'm still confused about electrical (I just got sidetracked for a while!)...

I was just (finally) planning electrical details with my contractors this morning, and happened to revisit this post this afternoon looking for amperage information on the Roburs, and I caught this:

Robert Goble wrote:Your cyncra needs a dedicated 240 volt, 40amp (or higher like 50 or 60 would be good too) line --- not 3 phase.


While I never meant to imply in my initial post that I wanted to run the Cyncra on 3-phase, I am curious as to why higher amperage for the espresso machine would be better. If I remember correctly from this morning, my electrician looked at the Cyncra specs and determined 40 AMPs would be ample (the cut sheet says, "36 Amps" for the 3-Group I think). Could someone explain why I would want more, and how much more?

And I'll keep looking through these posts, but if anyone has the info on the amperage for the 3-phase Robur, please feel free to share.

Thanks, guys!
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Postby barry on Wed May 09, 2007 1:13 pm

lee wrote:morning, my electrician looked at the Cyncra specs and determined 40 AMPs would be ample (the cut sheet says, "36 Amps" for the 3-Group I think). Could someone explain why I would want more, and how much more?


IIRC, the NEC requires that the load on a circuit total no more than 80% of the breaker rating. A 36-amp load would need a 45 amp breaker, which, afaik, isn't made, so you'd need a 50-amp breaker. The higher amperage requires thicker wires, too.
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Postby Brent on Wed May 09, 2007 2:21 pm

If it is anything like NZ...

At around 50 amps the plugs change. That is assuming you have 3 phase, neutral and earth plugs (5 pin) some motor plugs only have 4 pins. Most plugs here go to around 40, and from 50 you get different plugs.

My understanding is that this is to stop people plugging high power devices into low use outlets.

In this case you would reterminate the Robur plug to fit the higher rated outlet.

:)
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Postby Brett Hanson on Wed May 09, 2007 10:16 pm

Robert and Barry are both right and are using different sources to build a case for upsizing your circuit.

Robert has a lot of experience installing these very machines and he's suggesting that you provide a larger breaker and wire to eliminate any nuisance tripping of the circuit. If the Cyncra's full load amps tops out at 36 Amps (read: all boilers full-on, all pumps running at full output, all pids computing away, etc), you want to bump up the circuit and breaker at least to the next standard breaker size (in this case 40 Amps). For example, if you were to provide a 35 Amp breaker and the machine were to pull 36 Amps, the breaker would trip and your machine would be "off". Robert is suggesting that you consider a 50 Amp breaker because heating and pump elements have a tendency to spike their current usage when turned on or activated. As such, if you served the machine with a 40 Amp breaker and you flipped on your cold machine in the morning and then started flushing the groups, maybe the pump would spike and cause the combined load to exceed 40 Amps long enough for the breaker to trip. Sizing your breaker and wire to 50 Amps could prevent the circuit from causing a "nuisance trip".

Taking a different path to the same result, Barry is talking about how the National Electrical Code requires you to upsize the circuit to prevent nuisance tripping. In short, the Code is charged with preventing buildings from burning down. The Code is similarly interested in preventing nuisance trips because the authors want building occupants to be mindful when an actual electrical fault happens. If you're constantly having to reset your circuit breaker (due to a circuit sized too-low) and it becomes a habit, you won't notice when an actual electrical problem is happening and you'll fail to get it fixed before a fire breaks out or one of your staff is injured. There are different rules for different types of devices in the Code. For restaurant equipment, the Code gives the engineer of record some latitude for deciding how large to size the circuit- anywhere from 125% of rated load to 175%.

If your engineer suggests 125% is the proper rating of your breaker, then you would multiply the full load amps of your device by 125% and then round up to the next standard breaker size. Barry employs the reverse-math and takes 80% of the breaker size and matches it to your device.

To dive more deeply into this issue than necessary (really- this is a complete waste of time), you could work with Synesso to understand what the maximum full load current for your specific machine is (in a more detailed way than what is shown on their cut sheet). Will all (3) groups (the pump) ever really run simultaneously? Will all the boilers ever run at full output at the same time? You could spend a lot of time determining what the worst case current would ever be. My guess is that it will be a rare day that you max out all the boilers, pumps, and electronics at the same time. You would need stone-cold boilers, all groups flushing (cold water?), steam wands full open, etc.

Brent makes some good points about plugs. The good news is (1) you'll likely hard-wire your machine so plugs won't be necessary and (2) there is only one plug that will work with the circuit size you choose, so make your circuit decision and your engineer or electrician will tell you which receptacle you're getting.

At the other end of the spectrum, you don't want to size the circuit too big. For example, if 36 Amps is the full output, there is no need for a 100 Amp circuit to serve it. This would violate Code (you can only size up to the next standard circuit once your engineer has used his/her engineering judgement to choose a multiplier between 125% and 175%) because an arcing fault could take place between the breaker and machine and not enough current would be drawn to cause the circuit to trip.

And now for today's PSA...
Remember, it's the current that kills!
0.1 Amps = Unrevivable Death
This was rammed into my head every semester of electrical engineering lab, so I feel compelled to share it with all of you.
Last edited by Brett Hanson on Thu May 10, 2007 1:39 pm, edited 1 time in total.
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Postby Lee Corrina Cano on Thu May 10, 2007 5:54 am

Thanks for the responses, guys.

Brett, your explicit breakdown/explanation was especially helpful, and I've printed it out to review with the electrician.

As always, you folks are showing the depth of your knowledge and generosity. I certainly hope to be able to reciprocate once we have more experience under our belts!

Thanks.
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update

Postby Lee Corrina Cano on Mon May 14, 2007 6:07 am

Whew, have I been learning a lot about electrical service!

Just as an update, my electrician was already planning on putting in a 50 Amp breaker for the Synesso, so that was all good.

And since we have the service already, we're going to go ahead and spring for the 3-phase Robur. I'm sure it will be overkill for us at the beginning, but I'm hoping we'll grow into it in due course. Plus, it's a part of blurry plan to possibly lure some (humble) quality-oriented baristas to our fledgling shop (July opening?)!

Note: Chicago in the summer is a beauty... and we're not too far from the lake!!!
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Postby Brent on Mon May 14, 2007 2:04 pm

Brett Hanson wrote:Brent makes some good points about plugs. The good news is (1) you'll likely hard-wire your machine so plugs won't be necessary and (2) there is only one plug that will work with the circuit size you choose, so make your circuit decision and your engineer or electrician will tell you which receptacle you're getting.


But if you hard wire in, how do you take the machine away on holiday with you?

(our solution is a little one group with a tank, but I am sure some people won't want to do that)
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