What voltage should I run at?

[Voltrael]

I work in an industrial facility with the LV system at 480V. I can remember from a place I used to work that there was some theory about it being more efficient to run at a different voltage. Does anyone have any information on the theory behind that? I seem to recall wanting to run high, at maybe closer to 500V (10% increase) but can't remember the engineering theory behind it.

 

[kwired]

It is often desirable to run close to 500 when unloaded so that when loaded it hopefully doesn't drop much below 480, but having it drop to 460 really shouldn't be much of an issue most of the time, especially for 460 volt motors.

 

[Jraef]

Efficiency is something that is designed into the utilization equipment, changing the voltage doesn't change the equipment design.

There is some "junk science" crap out on the internet from people saying that by running your voltage high all the time, you will "save energy" because they think that current goes down when the voltage goes up (and they mistakenly equate current with energy). This is all bunk, ignore it. If anything, you may actually WASTE more energy doing this as things like transformers and induction motors will just run hotter at the same load, and that heat represents wasted energy.

kwired's comment is valid, but not from just the standpoint of increasing efficiency, it helps avoid voltage DROPS under load, which could have many negative effects including a loss of efficiency on those same types of equipment mentioned above. So for example if you start at 480V at the service entrance with no load and that drops to 460V under full load, you might end up with only 430V by the time you get to the motor farthest away from the service, that motor is going to run very inefficiently. So if you start at 500V unloaded and it drops to 480V under full load, then that farthest motor may drop to only 450V, which is within it's design tolerance.

 

[Voltrael]

Based on the posts here, and my complete inability to find anything to the contrary, my plan is to try to get each drop tapped to 480 at the bus, with a caveat that I will try to not be below 460 at any point downstream. Similar philosophy behind the 4160V and 2300V circuits.

 

[iwire]

Based on the posts here, and my complete inability to find anything to the contrary, my plan is to try to get each drop tapped to 480 at the bus, with a caveat that I will try to not be below 460 at any point downstream. Similar philosophy behind the 4160V and 2300V circuits.

Your question is way to vague to answer. It is the same as asking which color paint to use for a room.

Personal choice and a host of other items all play into it and any choice you make is a compromise.