[SML] Motors on UPSs

[Michael Sauder]

On Thu, Jan 15, 2015 at 10:41 PM, Jerry Durand via Stagecraft <
stagecraft at theatrical.net> wrote:

> Just a comment on the auto-taps.  I'm sure your electricians know about
> it, but just in case it's worth noting.  When you get a brownout and the
> transformer switches, your Amp draw will go UP by about the same
> percentage as the brownout goes DOWN.  Not a problem unless you're
> running close to full capacity and you have a deep brownout.
>

Yep. I'm a dodgy electrician, but I still knew this much, and told as much
in my email to the producers tonight.

*"I'm sure your electricians know about it, but just in case it's worth
noting."*

I've learned not to assume a single thing. My emails tend to be lengthy and
detailed (which sometimes means people don't read them carefully), but at
least then I can't be blamed for not throughly explaining something.

Despite this, the electrical drawings I received earlier this week were
full of errors, some major. How much of this was incompetence, how much was
lost in international translation, and how much of it was my own
inexperience, I don't know...

A side point I'm really curious about: When you read "220V 3 phase" do you
folks read that as "Each leg is 127V, any two of which give you 220V" or do
you read it as "Each leg is 220V, any two of which give you 380V"? (Convert
to U.S. figures as needed)

As you might guess, we need one interpretation (127V per leg) while the
drawings specced another (220V per leg). Which meant that a required 50kVA
transformer was not in the drawings, or budget.

Michael S.
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