A customer has Lathes, drills, air compressors, etc. most of the voltage are 230/460. 3phase Most loads are small 38a at 230v. The existing service is 120/240v 1phase. looking to upgrade service to 120/208 3phase. Will the 208v 3 phase on 230 or 240 3phase equipment and not effect equipment peformance. There will be one CNC later not sure how large
3 phase 120/208
- Thread starter mannyb
- Start date
- Status
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Your post is a bit unclear, lemme see if I can rephrase.
Will 230v 3 phase equipment run on 208V?
How will this effect the operation?
What if the loads are only less than 40A? Does this matter?
Will 230v 3 phase equipment run on 208V?
How will this effect the operation?
What if the loads are only less than 40A? Does this matter?
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
180105-1627 EST
mannyb:
Apparently all present machines are single phase 240 V.
Any that do not have high initial loads, and are not generally run at full load can probably run at 208 with no problem. This would include drill presses, sanders, small tool grinders, and hand tools.
Anything with a high inertia load, for example a radial arm saw with a large diameter saw blade might be a problem on start up.
An air compressor may have a high initial load. The air compressor motor probably should be replaced with a 3 phase motor, at least if it is in the 5 HP or higher rating.
If the 208 source is very stiff, little voltage drop under load, and you use low impedance wiring from source to the load, then the high initial loads may not be a problem.
At no steady-state condition do you want to run a load current higher than rating.
A future CNC machine should have input taps that allow 208 operation.
.
mannyb:
Apparently all present machines are single phase 240 V.
Any that do not have high initial loads, and are not generally run at full load can probably run at 208 with no problem. This would include drill presses, sanders, small tool grinders, and hand tools.
Anything with a high inertia load, for example a radial arm saw with a large diameter saw blade might be a problem on start up.
An air compressor may have a high initial load. The air compressor motor probably should be replaced with a 3 phase motor, at least if it is in the 5 HP or higher rating.
If the 208 source is very stiff, little voltage drop under load, and you use low impedance wiring from source to the load, then the high initial loads may not be a problem.
At no steady-state condition do you want to run a load current higher than rating.
A future CNC machine should have input taps that allow 208 operation.
.
Say you have a tool that draws 30A are 240V, that's 7.2kVA. To get the same power at 208V you need 34.6A. Not a big difference, but it gets larger with higher power equipment and with high starting requirements. If the equipment is designed for 30A max and it draws more with 208V that could eventually damage it.
MAC702
Senior Member
- Location
- Clark County, NV
Do you have a lot of 120V loads? Is there a reason you aren't considering the upgrade to be to a 120/240V Delta 3-phase service instead? The 3-phase machines will love it with no issues. There is just less panel balancing if you have a lot of 120V loads because one leg can't be used for them.
JFletcher
Senior Member
- Location
- Williamsburg, VA
Look at the nameplate. Most will be stamped "208 - 230/460V". If yours is, yes, it will work on 208V supply without affecting performance. You may want to check any control transformers as well for a 208V tap or switch vs other voltages.
I take it none of the this 3ph equipment has been operated on site since your customer has 1ph service? 38A, is that the total draw for all of the lathe motors, coolant pumps, etc?
What if compressor or machine reads 230/460v on you have 480v. Would that be a problem?
i agree let me circle back around. I got busy when i posted question. A customer has 120/240v 1ph service. They have some equipment they want to install with 3 phase 230/460 some equipment 240/480 3 phase mostly. My question should have been what voltage would be best 120/208 3 phase or 120/240 3 phase or I can bring in 480v then use XFRMS as needed. Most items are 230/460. I was looking to see what voltage best suits what I need. my concern is the 230/460v. The place is a basic machine shop/fabrication shop.
growler
Senior Member
- Location
- Atlanta,GA
You can probably start out with the size service needed for the whole facility. Is the place really big with a lot of long runs to feed these machines? Unless you really need it then going with 480V is going to be a more expensvie install because your are going to need tranformers and 480V panels, breakers, disconnects and most anything else is more expensive ( but you do get to save on wire size, service and feeders). All those machines that say 230/460 will run on 240 delta system but you may need to do a little work to retap some motors and controlls. What are they set up for now?One thing to consider is if they are putting all their machines in there now or are they planning on expanding in the future.
MAC702
Senior Member
- Location
- Clark County, NV
460 is a nominal voltage for our 480 actual.
230 is a nominal voltage for our 240 actual.
200 is a nominal voltage for our 208 actual.
So 230/460 is the same thing as 240/480.
It is still possible that you can use some or all of your "230" nominal equipment on a 208 service, but you should still find out if you really need to find out.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
You have your terms mixed up. Nominal is 120, 240, etc. Then comes service, followed by utilization.
It only has exisitng lighting. I am taking a stab at the calculations
Existing The warehouse is basically empty.
22-1000w fixtures lighting EXISITNG
20-120v recptacles ( new ) Non cont ADD
4- welding 12.3kw each 230v 33a 3p Non cont ADD
air compressor 230v 25a 3p motor load ADD
MORE TO BE ADDED
calculation (Let Me know What I am doing wrong Please )
general lighitng 22,000va
receptacles 20x180va = 3600va
compressor motor 25ax 230v x 1.73 = 9,930VA
Welders 12.3 VA x4 = 49200VA
Total VA = 84730/240x1.73= 204A
Existing The warehouse is basically empty.
22-1000w fixtures lighting EXISITNG
20-120v recptacles ( new ) Non cont ADD
4- welding 12.3kw each 230v 33a 3p Non cont ADD
air compressor 230v 25a 3p motor load ADD
MORE TO BE ADDED
calculation (Let Me know What I am doing wrong Please )
general lighitng 22,000va
receptacles 20x180va = 3600va
compressor motor 25ax 230v x 1.73 = 9,930VA
Welders 12.3 VA x4 = 49200VA
Total VA = 84730/240x1.73= 204A
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
No, the neutral needs only be sized to carry the imbalance. 220.61.
However, it can be no smaller than the feeder EGC sized per 250.122. 215(A)(2).
MyCleveland
Senior Member
- Location
- Cleveland, Ohio
Great table...is there not some text on this subject above the 430.xxx motor FLA tables ?
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
There may be, I do not remember seeing it, but IDK. Will look in a minute.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Yes, text states that the tables are based on rated motor voltages- 115, 230, 460 and such.
MAC702
Senior Member
- Location
- Clark County, NV
It's a relative term. 230 is the worldwide nominal often used for equipment labels. That's the context of the OP's equipment.
Your context is an American Standard reference. Many sources often confuse the terms "nominal" and "normal." Indeed, "nameplate" would be the same as "nominal."
Nominal and actual are rarely the same. Just like with pipe sizes.
Last edited:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Okay, so NEMA, ANSI, and NFPA all agree but are incorrect in your opinion......
Of course nominal and actual are rarely, if ever, the same. Nominal is the “ ideal steady” state voltage while actual is the “real ever changing” state.
- Status