What voltages for USA ?

[Ken Moore]

I have not seen 600 but I worked on a OLD reciprocating compressor once (IR) it was 2160? I know it was over 2000 and I think it was 2160, the cylinders were about 3 feet tall and maybe 2ft across.

It had a time delay on the start, one morning I pushed the start button and started to walk out the room, then I remembered that I need to check the oil so I hit the stop button at the same time it started up.... there was a blue fire ball that lit up the whole room

Most likely 2300 or 2700. Very common around 1910ish. I worked at a Zinc Smelter built in the late 1800's, that switched from DC to AC in 1911, they had 2700 mains, with 2300 volt motors.

 

[joseph_e2]

...If it is correct that 480V is more or less the standard (albeit with exceptions) I will probably end up with offering 480V per standard.
If this covers 90% of potential customers it will be acceptable.
Any other voltage will require a special price.

In my experience, that would work well.


Another anecdote: at my last place, we had some big forming presses (500-600 ton flywheel presses) wired for 240VAC because they came from another plant that was primarily 240V. To get that voltage (long before my time there), they put in a delta-delta transformer with a corner ground. The first time an electrician encountered it, he was super confused. It didn't help that the grounded leg wasn't identified in any way and was fused in the disconnect switch (a no-no: grounded conductors aren't supposed to have overcurrent protection unless that protection also opens the ungrounded conductors). After having our arc flash study updated, we were able to re-wire those presses to 480VAC which had the added benefit of reducing the flash hazard boundary from 20ft to a couple inches.

 

[Gene Bond]

The US is a 'Wild West' when it comes to 'standard' voltages.

480Y277 is certainly the industrial standard.
208Y120 is a commercial standard.
240/120 1ph is a residential standard.

BUT, you'll eventually run into:
240 3ph Delta which is either corner grounded or 1 phase center tap grounded.
460 3ph open delta
460 3ph corner grounded
460 3ph open delta corner grounded (2 transformers)

My suggestion: Build your Industrial Machine to be supplied with 460Y277, and suggest a transformer (Delta/Wye) if they have an odd voltage.

Just my $2 worth (covid-related inflation included)

 

[robertmee]

I have an operating customer near Boston Mass that's entirely 575VAC. Plant was built in the 40s, but we run brand new 600V powerflex drives. Alot of the equipment ran on Automax PLCs on control net.

 

[Christoff84]

Our plant is 575/600V (both are used interchangeably). We're not really concerned with machine voltage (600/575/480/400 etc), that's what transformers are for. Mostly we like to see 24VDC control systems, cabinet segregated between high and low voltages, and the CE, cUL, or CSA markings on components to pass a field inspection.

 

[JesperMP]

It seems that it is quite common to just add a transformer to adapt to the onsite supply voltage.
That makes it easier for me to stick to the standard of 480V.
But I do find it peculiar. When you have a production facility with a 'non-standard' voltage and many machines, then you have a transformer in front of many of the individual machines ?

 

[Gene Bond]

Yes, very common. In some cases, the OEM supplies the transformer as part of the machine, especially when VFD's or DC drives are supplied. In other cases, the installing electricians may supply the transformer.

But, since most plants are wired for 480/277, it's only the odd that need them.

 

[I_Automation]

I have seen shops where up to 90% of the machines have a transformer. It is common to spec a transformer when buying a machine.


One customer has mostly Japanese stamping presses and robot welders.


All the presses are 200V 3Ø while the robots are a mix of 208 or 240 - except the one that is 380. Even half the machines in their die repair department have a transformer.


Oh, that shop is 495V, not 480V, and the only place I have seen with 495 and a lot of VFD's they have give overvoltage faults regularly.

 

[Robb B]

Canadian reporting: there's no 575V in Canada, popular 3 phase supplies are 480V and 600V, sometimes 208V for commercial services. In BC in fact, BC Hydro is moving away from 480V secondary transformers, meaning all new services for 3 phase will be 600V, up to the customer to supply their own step down after that. They might still supply 208V for commercial customers, I'm not sure on that.

 

[Tom Jenkins]

575 VAC is 600 VAC, just like 460 VAC is 480 VAC. The higher voltage value is the nominal supply voltage coming from the power company. The lower voltage value is the utilization voltage at the equipment and includes an allowance for voltage drop in the internal distribution network.

 

[theColonel26]

Yes what Tom says,

120/240 1ph is Nominal (110,115,120/220,230,240) (Residential)
120/208 3ph Wye is nominal (200, 208)
120/240 1ph/3ph Delta (Center Tap) is nominal (wild leg is not used for phase to ground... normally)
277/480 3ph Wye is nominal (460,470,480)
240/480 1ph/3ph Delta (Center Tap) is nominal (wild leg is not used for phase to ground... normally)

Then in Canada they also have
347/600 3ph Wye is nominal (575,600)
300/600 3ph Delta is nominal (I have never heard of anyone using any phase to ground on this but maybe someone does)


I am kinda curious what Peak voltage to ground you would see on a Delta Corner tap, but I am too lazy to google it right now lol

 

[Gene Bond]

<snip> I am kinda curious what Peak voltage to ground you would see on a Delta Corner tap, but I am too lazy to google it right now lol

It's the line voltage... 480 on L1 - Ground, 480 on L2 - Ground, L3 = Ground/Neutral

 

[lfe]

Here in Europe, new installations no longer usually have neutral, 400V III 50Hz, it doesn't matter if it comes from a delta or star transformer.

For lower voltages, then you need a 400V primary transformer or power supply with 400 V input

 

[I_Automation]

It's the line voltage... 480 on L1 - Ground, 480 on L2 - Ground, L3 = Ground/Neutral

Technically, but in reality by the time you get to the machines in the shop the ground could be off.


The shop I mentioned that has actually 495V Delta service gets the following readings phase to ground at their machines:


L1 20V [which at the pole is 0V as this is is grounded leg]

L2 455V [495 less the above float]

L3 515V [495 PLUS the above float]


That shop did finally call in an engineer from the utility to investigate and they are replacing and correcting the incoming service over the holiday shutdown next month.