design/build pointers

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quinn77

Senior Member
Just got contracted to design/build metal fab shop, ( large machines...cnc, aqua jet, brakes, welders, etc...) anyone have any pointers with calculations, design, etc... Ive just never designed systems of this nature. Thanks fellas.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Semi-Retired Electrical Engineer
I would allow for the possibility of all machines running at the same time, when I calculated the total load. Also, I would look into the question of whether the owner is likely to be moving equipment around from time to time. If so, then perhaps feeding equipment via an overhead feeder busway, rather than by conduit and wire to specific locations, might be a viable option.
 

satcom

Senior Member
Just got contracted to design/build metal fab shop, ( large machines...cnc, aqua jet, brakes, welders, etc...) anyone have any pointers with calculations, design, etc... Ive just never designed systems of this nature. Thanks fellas.

Are Ec's allowed to do design work in Texas? Are you required to have E&O coverage?
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I figured buss duct for the one we laid out. They seemed to be always moving or adding. Price was high at the time but I know they wished they had gone ahead with the project. We can't use the term Egineer unless we are one. Generally our license does allow us design build in NE.
 

quinn77

Senior Member
Are Ec's allowed to do design work in Texas? Are you required to have E&O coverage?

Yes, as long as the bid does not exceed $30k, an engineers stamp is required after that. If that happens...i'm covered. I have good relations with one of the most sought after designer/engineer in these parts.:)
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
101114-1532 EST

quinn77:

The following comments are not meant to influence your design. Just some background.

If you take the full load ratings of all the machines and add them up, then you will over design the system in terms of its real need. But this is probably a good approach.

In my son's shop all the CNC machines are ball park 20 HP units, six of them. Practically never are any of these run at this power level for very long. Other machines are a few HP to 20 HP. Welders might be 50 A peak. The supply is 200 A 3 phase 240 open delta. Because of a long feed line the inrush on start-up of some motors causes slight light flicker. I think the line from the transformer to the main panel is about 450 ft of 0000 copper.

He has no internal power problems effecting the CNCs or computers. Only external, meaning before his transformer, power problems that cause machine problems. These days such occurrences are very rare. A few years ago there were substantial problems because of poor connections on the secondary side of the pole transformers.

Always when there electrical storms all CNC machines are shut down. At the occurrence of the great northeastern blackout a few fuses were lost and and one Ethernet switch.

The 200 A service is adequate for his needs.

If he had fully loaded machines running continuous production, then a larger service would be appropriate with the transformer closer.

From an energy conservation perspective in a high volume production environment I would like to see the CNCs all use a common DC bus voltage, interconnected at the DC bus level, and a high voltage float battery or super-capacitor on the bus. Then the deceleration energy would be shared by all the machines. There are AC regenerative systems, but I have not seen any in operation. This DC bus could also be fed from a PV array, but thru DC to DC interfaces.

Lathes doing complex contouring, and mills doing short drill operations with many tool changes, all produce a lot of regenerative energy.

In another thread a Detroit area person said that OSHA required their plant with fixed machines to be piped rather than cord attached.

.
 

cadpoint

Senior Member
Location
Durham, NC
Is this an existing building or out of the ground, either way this might will be a refresher or a eye opener as to the design aspects of things. The following is a list of things that might or might not be of considertion but might well effect your electrical package.

How will the building be classified, will the building be sprinkled, or other type of fire protection? Will machine chemicals
cause any consideration on any wiring methods?

Where the power pole or source to be on the property? Who's to set poles or run the underground from POCO service?
Where's the Data and Sanaity Line's, what are the requirement for Data/Phone (usually sub'd out but you run the conduit).

Don't let them put the power and the trash dumper in the same service area, if it's at all possible
IE don't mix power and oil- chemicals in outside power area. Ballards for power protection if outside?

Depending on State Building Codes, handicap toilets, means of egress lighting requirements might well be needed
or to be upgraded!

The HVAC contractor has some important numbers for you! As does the Plumber!

What about security wiring? Outside lighting, signage.

If you have a good set of drawings of a previous job just open up the Site, electrical, architecural, reflective ceiling plans, review them and you should come up with the same as stated above and more of your potential job!

Good Luck!
 
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