Pete C. wrote:


The allowable voltage range for your 240/120 3ph delta wild leg service
is from 220v-254v at the service entrance (from a chart referencing ANSI
C84.1-1989). If the service is considered acceptable over a range of 34v
I just don't see a 32V difference between services as significant.

Large motors are built to handle widely varying power and load
conditions, and power supplies for controls either have plenty of tap
adjustment range for older machines, or switching supplies for newer
machines that are happy on anywhere from 98v - 250v. Your motors might
run a few degrees warmer but still well within their specified operating
range and your controls should be perfectly happy as well.


Most machines I've seen can accommodate a wide input voltage range, for
the few machines that can't you use the small inexpensive buck/boost
autotransformers.

We've already kicked that around. Why buy more transformers when you can
get the proper voltage?


Again, because not many machines would actually require it, and the fact
that your "proper" 240V service is allowed to vary over a 34v range
anyway.

Peter,
Do you think it would be OK to run the 240 motor on 197.6V ? Because
that's what could happen when you hook it up to a 208 service. Most all
power companies have a 5% tolerance on their service voltage. So a 240
service can go from 238 to 252. And a 208 service can go from 197.6 to
218.4. The purpose of a 208 service is to serve buildings with large
lighting loads and small 3-phase loads. There is a lot of commercial 240
3-phase and a lot of houses that have their own 3-phase wells will also
have a grounded center tap delta. I happen to have a 10HP 3-phase pump
with a straight 3-phase service, 3hot wires and no neutral to the pump.
The bank across the street from my house has a 25KVA and 2 10KVA
transformers, in a center tap grounded delta. My house 120/240 single
phase also comes off of this same bank.

Don