Tuesday, March 10, 2009

UPS Rules:

1. The UPS that cannot fail dead, will.

2. When you complain to the Power gang about their UPS failing your well-behaved three-phase load, rest assured that when power comes back up, you will discover 75% of your load is on one phase and the other 25% split between the other two.
2.1. The Power boys will be barely able to restrain their snickers when pointing this out.

3. There will be a spare UPS they never told anyone about, tucked in an obscure corner.

4. It will be all charged up, in Bypass and ready to go online...except two phases are flipped between input and output, so if the make-before-break Bypass switch were to get switched, there would be a brief flash and puff of smoke.
4.1 Your guys will be barely able to restrain their snickers when pointing this out.

5. "Ready to go online," even after you restack all the loads so the phases can be swapped, actually means "about two hours' downtime."
5.1 Power will not have told the brass this sad and awkward truth.
5.2 You will have to.
5.3 They won't like it.
5.4 By then it will be too late.
5.5 And it will take even longer than you told them it would.

Yayy, hooray! Good newses for all! We have a new UPS online and all the loads are balanced between the phases on all the UPSes, or at least close enough to keep them from acting up. (If I keep smiling and talking fast, maybe the Chief won't point out it took three days and some graveyard-shift overtime to get back to where we were already supposed to have been).

Oh, the glamor and fame and red-blooded adventure to be found travelling between the stars! Of all the fictional prophets of the Space Age, George O. Smith* turns out to have got it right -- and I think he might've had some inside info.
__________________________________
* I'm sorry to see most of the Web bios barely mention his "day job:" he was a EE, one of the men who made the WW II Radio Proximity Fuze work: it amounts to a tiny, vacuum-tube radar set, loaded in an AA shell and shot from a gun! His fiction is grand fun; if you like my reports from the Engineering Department of the USAS Lupine, you'll enjoy visiting his cast of characters.

GLOSSARY

UPS: Either "Unlikely to be interrupted Power Supply" or "Unprovably interrupted Power Supply." It depends on what just happened and who saw it.

Three-Phase Power: AC with three "hot" leads and one neutral. The AC waveform on each hot lead is 120 degrees out of phase from the other two and if the load on each one is of identical impedance, the neutral current is zero. For complex reasons having to do with the way toast falls butter-side down, this never happens. We like three-phase power 'cos it makes electric motors happier. Also the kids dig it. Or not.

Restacking The Loads
: Rearranging the connection of loads to the circuit breakers in a panelboard ("fusebox") in such wise as to try to get zero neutral current, see above. Close counts, especially since it is the best you can ever do.

My Career
: Spent doing things so obscure it requires a glossary just to complain. I should have T-shirts with footnotes on them.

17 comments:

Joe said...

Proving once again that a good engineer always hides a spare or two from inventory control!

Anonymous said...

What do you have against men in short pants in brown trucks?

Shootin' Buddy

Aaron said...

Ugh, of all the cantankerous hardware one must deal with on a ship, anything meant to supply, transfer, store, step up, or step down the elctro-juice is always the worst.

At least there was no puff or smoke or a generator jumping its mounting when getting paralleled to the bus.

This time.

D.W. Drang said...

I was just going to say, you might want to include a glossary.
"Uninterpretable Power Supply."

Anonymous said...

Imperturbable Power Supply?
Did you just say that?
I like it!
Wish mine were more so.

sam said...

"Restack the load?" That must be what my power geeks call "energizing" the UPS.

My mind is boggling at what the power step-down from a fusion reactor must be. Those transformers must be huge, and the heat output? Good thing space is mostly cold.

STS-125 is scheduled to launch May 12. Not exactly a June wedding, but close.

D.W. Drang said...

Er. Um. "Uninterruptible" Power Supply.

"Uninterpretable" is what my handwriting is.

Roberta X said...

I liked the first word better, D. W.

Sam: but are you of good family?

Old Grouch said...

Sometimes called "[unprintable] power supply" when it gets flakey.


-----
"T-Shirts with footnotes" snork!


Tw: "anterma"

The terminal you use to hook up the antenna?

Joe Huffman said...

I understood just fine without the glossary. But of course I'm "special". I gave up trying to talk about work with most other people long ago. You could see them straining at "signal to noise" ratio and the eyes glaze over with "notch filters". "Phase locked loops" and "operational amplifiers" would cause them to just ignore you.

The other day Barb asked what I was thinking about and I said, "Work" thinking that would be enough. "What about work?"...

I told her she didn't really want to know but she insisted so I told her the truth, "Can I use a KD tree to store and retrieve tiles from a spherical surface? And what equations and algorithms do I use for measuring distances between points and tiles? It turns out Haversines are required and that might make the computational load a bit heavier than we planned."

shrug

"I told you that you didn't want to know."

Sometime we technical types live in different worlds. The sad part is that I often prefer the imaginary (it has imaginary numbers, right?) to the real world. People are so unpredictable and difficult to understand. Computers and electronics are easy by comparison.

sam said...

A few months after I left the job where I worked with the big UPS, there was a big storm.

Power grid failed, and the backup generator failed, too. UPS batteries carried the load for a couple of hours, then, 'donk.' Everything was down. Website, call center IVR, DB servers, e-mail, everything.

Many eggs, one basket. Like I told them before I left. Fast, cheap, good. Pick any two.

RobertaX, my almost, nearly betrothed, I guess it depends on what the meaning of 'good,' is. Do no criminal "convictions" count?

I was born in Minneapolis, if that provides any insight. I've eaten my share of lefse. Pass on the lutefisk, though.

WV: stersess - stress + curses?

Hank Morgan said...

Tshirts with footnotes would be... interesting on your frame.

Three phase? Three phase is nice because you can easily turn it into almost anything with little power loss, and send it long distances at high boltage over the teeniest of wires and make BIG HORKING SPARKS with it.

Yeah, I know, the big horking sparks are not normally to be desired.

Anonymous said...

T-shirts with footnotes.
You have really nice
asterisks.

Op Cit, or Ibid?

rickn8or said...

Big horking sparks?

When did YOU ever see me work on an airplane??

wv: "eptic" That indeterminable amount of time waiting for the EPT strip to "+" or "-"

Aaron said...

All anyone ever needs to know about electrical and electronic gear:

Black smoke makes it work
If the black smoke is leaking out, you should cut off the juice
Blue sparks are pinhole leaks

batteryguy said...

As a UPS, battery, and power quality tech-type I resemble all of these remarks.
WV: ninhant
An unusually silly ghost?

Ian said...

BTW - my copy of the '76 release of the complete VE is one of my treasured possessions.

I still get a giggle from the numbers thrown around when they're messing with the big capacitor. (physically small, but measured in farads. No prefix)