Selecting the distribution voltage should factor in the decreased circuit investment, lower electrical losses, and better voltage regulation realized by carrying power at a relatively high voltage to a point as close as possible to where the power will be used. This may require using two or more different voltage systems in the same plant. Transformers can be used where voltage levels need to be changed.
The system can be supplied directly from the power company at 240 Volts or 480 Volts if the load is small enough and feeders are short. Larger kVA loads and greater distances may require in-plant distribution at medium voltages. Serving a load in excess of 1000 kVA at 480-Volts or about 500 kVA at 240 Volts would likely be more costly in plant investment than going to a higher distribution voltage. We shall see, too, that choosing 480 Volts for the motors is often better than using 240 Volts.
