Voltage Ratings: 110/115/120, 220/230/240 or 440/460/480

[garbo]

For 208Y three phase motors under ~10HP what I typically see is manufacturers cheating and sell you a 220/440V motor.
They call it a "tri-voltage", and stamp the nameplate 208-230V / 460V and thats when I use the 208V table in 430.
When I see a a tri-voltage nameplate like that I just think of it as a 220/440V rated motor.
To me a "tri-voltage" motor is not truly rated for '200V' and your voltage drop calcs need to account for that, as they probably wont really run well with voltage sags allowed in the ANSI C84 spec for 208Y/120 nominal system.
A true '200V' motor designed for a 208Y/120 nominal system would have a 200V nameplate indicating it does comply with ANSI C84 voltage range B minimum of 180Y/104V and then I use the 200V table.

Years ago I did a few weeks of work in a small plant that had a 800 amp 120/208 service and a lot of the motors were only stamped 240/480 volts. They probably burnt out the same amount of these motors during summer as the other 9 months thinking due to voltage would be below 200 volts. The local utility company did not off were any help. Finally convinced them to only order motors rated for 208 volts and stay away from the motors stamped 208/240 480.

 

[eric stromberg]

And after all this, we are seeing more non-US equipment. I've worked in Brazil with 220/127 and 440. The equipment was rated 440 and the transformer secondary operated at 455. Europe, with 400/230 and 690/400. But the 230 in Europe (used to be 380/220) is Line-Neutral. I have customers who want to connect European 230 L-N equipment to 208 with a boost transformer. I don't let them. There are transformers available with U.S. primary voltages and European secondary voltages.

 

[tortuga]

And after all this, we are seeing more non-US equipment. I've worked in Brazil with 220/127 and 440.

Regarding Brazil a question I have always had is what do they provide in rural areas without 3 phase overhead?

Here in a lot a rural areas we just have one or two primary and a neutral, so to run a 3-phase pump we do a open wye/ open delta.
With 220Y/127 do they ever do that with a open wye primary / open wye secondary ?

Do they offer split phase where there is only one primary and a neutral like on a UG loop feed?
I have herd some parts of Brazil are '220 only' so perhaps for rural areas they don't bother with split phase and just have a single voltage secondary? But then that changes the rating of their equipment of course.
To make 127/220 split phase one would need transformers with 90% taps at each secondary coil end, which I suppose is possible..

 

[don_resqcapt19]

And after all this, we are seeing more non-US equipment. I've worked in Brazil with 220/127 and 440. The equipment was rated 440 and the transformer secondary operated at 455. Europe, with 400/230 and 690/400. But the 230 in Europe (used to be 380/220) is Line-Neutral. I have customers who want to connect European 230 L-N equipment to 208 with a boost transformer. I don't let them. There are transformers available with U.S. primary voltages and European secondary voltages.

Because of this, I submitted a PI to permit the nameplate currents to be used for the Article 430 motor calculations as these non-standard motor voltages do not have their currents shown in the Article 430 tables. CMP 11's rejection statement seems to say we can't use those motors in NEC applications.

Public Input No. 3662-NFPA 70-2023 [ Section No. 430.6(A)(2) ]
(2) Nameplate Values.

The motor nameplate current ratings shall be used to determine the values for the following:

1. Separate motor overload protection
2. For motors built for low speeds (less than 1200 RPM), high torques, canned pumps, or multispeed motors, the following:
   1. Ampacity of conductors
   2. Current ratings of switches
   3. Current ratings of branch-circuit short-circuit and ground-fault protection
3. Large motors exceeding the values in Part XIV, and motors using voltages not listed in Part XIV shall be permitted to use the nameplate current rating for conductor sizing.

Statement of Problem and Substantiation for Public Input

There is more and more equipment that originates in foreign countries being installed under the rules of the NEC. In many cases these motors have operating voltages that are not standard in the US. Without this change there is no code compliant way to install this equipment as the current code only permits the use of the currents shown in the Part XIV Tables to size the motor circuit conductors.

Resolution:

The NEC contains the motor types and voltages approved for applications for the proper installation per this code. The addition of other motors cannot be accepted without further clarification on where they would be used and if they can be protected by the full range of motor controllers.