"Pete C." wrote in message
...
Harold and Susan Vordos wrote:

"Pete C." wrote in message
...
Harold and Susan Vordos wrote:

snip----

I think you're under the impression that a motor will run hotter if it's
strapped for it's lower voltage rating. A motor should run at the same
temp for the same load and duty cycle conditions when operated at any
voltage it can be strapped for.

I fully agree, but I have no motors that can be strapped for 208. As I
said, my Bridgeport is wound for 230. I don't recall what the Graziano
demands, and the motor is internal--not readily available. I just know
that it runs well on 240, so why risk anything? The induction furnace is
wired 220/440. It would be within range, but the huge amperage demand
makes running at a slightly higher voltage an advantage over running lower.
Not necessarily for wire size, but, again, for heat control.


Operation at the higher voltage setting is for the benefit of smaller
wire gauge to feed the motor, lower voltage loss on those wires and
smaller switch gear to service it, not for the benefit of the motor.

I understand that, but the cooler operation is certainly a benefit.


Again you're assuming that most machines will require the transformers,
which is not the case. The hotter part is a small amount, perhaps
significant for a big shop in the desert, but not significant in most
cases.


No, what I'm assuming is that the majority of the machines would be running
in the tolerance zone, unnecessarily. Given a choice, why would I want any
of my machines to run under voltage? Even within tolerance? Over voltage
is far superior to under voltage if one must deviate from the ideal.


I think that any older motors that are truly rated for 240V are also old
enough to be overbuilt beasts from the days when the line regulation was
nowhere near where it is today and consequently would likely not care
about running at 208V which is likely what they saw anyway on old
services with significant voltage drops within the building.

Could be, but I'd not be willing to gamble on it. Good example is the
induction furnace, although it's not one of the machines that falls out of
the tolerance zone (220/440 in this case). The motor generator weighs
almost three tons, and is water cooled, not fan cooled. That means it has
the potential to run hotter than I would like because it relies on heat
conduction with small coils of circulating water wrapped around the exterior
of the assembly. Adding any unnecessary heat to its operation would not be
in my best interest, especially if it had the potential for failure. I
can't speak for you, but I couldn't afford to pay for a rewind on something
of that magnitude.



Tell my friend in Utah that he only imagined the problems he had with
his
CNC grinders when he moved his shop to one wired wye. You make light
of
it, but it was a serious problem for him. His machines wouldn't run.
I
do not recall how they rectified the problem, this was about 12 years
ago.

By changing the taps on the control transformers within the machines and
adjusting the set points for the motor starters?

Dunno. As I said, I don't recall, but he has since built his own place and
has it wired according to his needs. Can't help but think it's delta, but I
couldn't swear it is. For all I know, he may be wired 480. I'll try to
remember to ask him the next time we talk on the phone.


Actually if they are installed integrally to the machine then they would
bypass any licensing requirement. Licensing requirements do not extend
past the power input terminals on the machine. Bolt the boost
transformers to the side of the control cabinet and run all the
connections inside the cabinet and they become part of the machine tool.

All well and good if you choose to use a wye service, but I chose to
eliminate that problem. I'm as happy as if I had good sense. Even *if*
one can get around the licensed electrician, you still face the cost of the
buck/boost transformers, which, at a minimum, would cost at least $300 per
machine, assuming you could get away with two instead of three. You also
have the cost of mounting them, and the inconvenience of them being in
place, adding considerably to the bulk of the machine, with no benefits. No
thanks.

I think my main point is that I feel the Wye system would have served
your needs equally well and would have simplified the installation by
avoiding your use of separate panels for your single and three phase
loads to avoid the wild leg issue.


Wrong! I have *no* wild leg issues. In fact, my split panels provide a
good an valuable service beyond just addressing that problem. I'm on a
demand meter with my 3 phase, but not the single phase panel. The
moment
I go above 50 KW (my induction furnace is a 50 KW unit), I pay more for
my
power. The way I've wired the shop, I avoid the demand load except
where
absolutely necessary, which is for the 3 phase equipment. My lighting
load
alone could reach about 75 amps, if I was to run all my fluorescent
lights
at one time. Each one is individually switched at the fixture so I can
use
only those that are necessary. In turn, they are wired in six banks, so
each series (according to shop location) can be switched at the door.

And you're paying extra for the second service (meter) vs. a single
meter if you used Wye service. The whole peak meter thing can get pretty
hinky, particularly when it is based on rolling averages, not hard
setpoints. If it's based on rolling averages then a consistent lighting
load has little effect. You really have to analyze your loads to see
what is best.

Nope! Wrong again. I am paying for two services in spite of my choice of
delta over wye. *ANY* 3 phase service is considered industrial where we
live. Had I run everything through the CT can, avoiding the meter base, I'd
be paying for my power at a higher rate because I'd exceed the maximum
(demand meter). Our meter base is a 375 amp unit, so we feed both the
shop and the house from it, at a residential rate. It's simple------if I
wanted three phase service, and I did, I had to pay for two services, like
it or not (and I don't). As much as I may not like the cost, I'm very
happy to have the convenience. I explored the idea of phase converters and
quickly dismissed the idea. Way too expensive, considering the load I had
with the induction furnace. I had two choices had I chosen phase
converters-----buy one huge unit and pay for the idling current endlessly,
or buy a few small units and bring them online as needed, still paying for
idling current. It was cheaper, and far more convenient, to pay for three
phase service.

To the best of my knowledge, I chose the right service for my needs.
Considering I have nothing that is wired for 208, nor can any of it be
rewired to accommodate that voltage, I sure as hell didn't want it in the
shop. If industry today is headed that direction, and machine tools are
so wired, that's a whole different situation, and I'd have no quarrel with
the choice. With the machines I have, that wasn't one of the options, and
I sure as hell wasn't going to spring for transformers that weren't
necessary, not when all I had to do is request the right service.


If you've got individual 50KW loads you may well be big enough to have
benefited from 480V service.

Again, a judgment call. I have one device with that load. Why would I
pay for 480 service, add an additional panel, then transform for everything
else? Personally, I think I made some excellent choices. Everything I have
runs as it should, and I haven't filled the shop with unnecessary
transformers. Idling current alone would have been expensive in the long
haul had I chosen that path. I have only one machine that *requires* 480
volts, a German made universal cylindrical grinder, which cannot be strapped
for 240 volts, or anything within reason. The only time the transformer
will be energized is when I use the machine. There will be no idling
consumption otherwise, so I won't be paying for making heat. Regardless of
your opinion, I feel I've done a damned good job of addressing the problems
at hand. Your bias against delta service seems to be a much greater
stumbling block for you than my choices are for me. Very strange, Pete.
However, I think if you visited my shop and observed how nicely it all has
come together, I think you might find yourself agreeing that I did the right
thing. :-)

Harold