On 3/15/2018 11:36 AM, danny burstein wrote:
In TimR writes:

In a housing development at what is essentially a campus, we fed 3 phase power to individual houses because of going to 208V airconditioners. I think we got a better price on a bulk buy of the units.

What we found is that everybody complained their dryers didn't work right and their ovens took too long to warm up. Their appliances expected 240.

For a straight thermal load like an over or dryer, that drop
from 240 to 208 is actually pretty messy.

At first glance you'd think that 208/240 = 0.8666.., or about 13 pct,
so to first approximations 13 pct longer to heat up.

However, wattage is amperage times voltage. And both of these [a]
are dropping by that 13 pct.

So the final wattage is.. 0.86... times 0.86... = 0.73.

So more than 25 percent longer.

[a] neglecting the very real issue that in many of these
items the resistance changes with temperatur...

As a side note, we installed a "240v" air conditioner i
a NYC building that had three phase, so it was being fed
at the equivlanet of 208.

We very specifically asked the sales rep AND the manufacturer
if this would be a problem. They said it was fine.

It wasn't.


https://www.larsonelectronics.com/p-...ps-5060hz.aspx