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Posted By: Joe Tedesco Power Quality Primer - 02/08/01 01:24 PM
The following site includes an interesting article covering the subject of power quality.

Look here for the article:
http://www.copper.org/pq/primer/


[This message has been edited by Joe Tedesco (edited 02-27-2001).]
Posted By: sparky Re: Power Quality Primer - 02/10/01 12:57 AM
A good fundamental bookmark Joe !
Posted By: sparky66wv Re: Power Quality Primer - 02/11/01 04:26 PM
I just had my other question answered!

Great article so far... I must continue my reading now... I'll probably have questions when I'm done...
Posted By: sparky Re: Power Quality Primer - 02/11/01 04:46 PM
66', so how did the pharmacy make out??
Posted By: sparky66wv Re: Power Quality Primer - 02/11/01 05:55 PM
Won't be taking care of them until Monday after they close. Trying to gather info on how I should approach the problem...

"Power Quality Primer" has lots of great stuff that's helping me...

I'll still have some questions though...
Posted By: sparky66wv Re: Power Quality Primer - 02/11/01 06:44 PM
Here's my plan...

Seperate the computers from the faxes and printers.

Run dedicated neutrals and an ISO ground as well as an equipment ground with a single hot conductor in its own conduit for each circuit I need. (one should be enough, the printers and fax can stay on the old circuit. Only three computers share the new circuit.)

Put the computers on ISO ground outlets.

Warn against the use of cheaper UPS devices (?) and reneg on my statement that UPS's help condition the power. (My tongue tries to be smarter than my brain sometimes...)

Quad receptacles are already there. Should I use seperate boxes, or can I convert one receptacle for computer use and one for printer use?

May I use 12-4 w/G MC Cable and use the red for the ISO ground? The last twenty feet is impossible to pipe.

Do I tape the red wire if I'm allowed to use it for the ISO ground?

Should I go ahead and file a power quality complaint with the PoCo and get an oscilloscope on site?

What else should I do? This is a valuable customer...
Posted By: sparky Re: Power Quality Primer - 02/11/01 10:25 PM
hmmmm,

66'
does any other biz share the secondary of the utility t-former serving the Pharmarcy?

would Iso-grounds really help, if in fact the real problem is the systems grounding in the first place?

Can you introduce a load to assess for problems pertinent to a bad connection?

I've seen a lot of green-tapped red conductors used for Iso-grounding...
i'm just as guilty if in violation...

I guess i have more Q's than A's here....
Posted By: sparky Re: Power Quality Primer - 02/11/01 11:06 PM
Quad receptacles, converted to Iso's ? I guess they can share a "box" ground, and have seperate Iso-grounds....

UPS ? i've cruised through a few sites in the past, sent a few e-mails...maybe i'm sold easy here, but i thought that they could cure the common cold.
Posted By: sparky66wv Re: Power Quality Primer - 02/11/01 11:41 PM
I guess I'm defeating the purpose if I put the computer recepts and the auxillary (printer, etc.) recepts in the same box. The site mentioned above has a pic of one sharing a housing, so I tried to use logic again...Oooops!

Yes the business shares the panel AND transformer with the doctor's office next door.

Should I take a known load and compare readings on both ends of the existing circuit? How much of a load do I need? Something steady like a light bulb, or larger, like a 1.5HP motor?

I'll tear into J-boxes and see if I can find a bad connection, incidentally, only one computer on the circuit is having the problems.

Unfortunately, my old boss did the original installation, and he is known for being maticulous. If I find a loose connection, I'll have to ask him who his helper was at the time...
Posted By: sparky Re: Power Quality Primer - 02/12/01 12:36 AM
I find myself on a number of calls just like your describing here.

Usually i will listen to the customers as to the signs and symptoms . This in itself can run from an informative diagnostic history, to a twilight zone rerun, depending on the person and problem, we've all been there.

My next step is to assess if the situation is an isolated circuit, and or device, machine, etc. , or if it is a system failure.

Many of these intermittent ordeals will cease to occur the moment i arrive, so in lieu of monitoring equipment, i sometimes try to recreate and/or alter the scenario.

I have run an extention cord to the panel from suspect circuits in the past, and used my PVC pipe heater, a good steady and known resistive load, while metering the panel.

This sort of thing may weed out a bum circuit.

I would consider looking for a large draw at the doc's office, does he have an x-ray machine ? autoclaven? maybe there an elevator motor cycling ?

I went crazy at one place until i heard the owner say that things had screwd up right after a lightening storm, and by golly, it was the UPS itself that had gone bad.
Posted By: Bill Addiss Re: Power Quality Primer - 02/12/01 03:43 AM
I have a small ups that I was going to have someone look at but haven't gotten around to it. I was at my brothers' company trying to figure out and label circuits for him and there was one We couldn't find for a good hour. We had a calcuator plugged into a receptacle and were watching it as We flipped the breakers. Nothing turned it off! The breaker He told me it was did not turn off the calculator. After insisting that it was the right one We shut it off and I pulled the breaker out of the panel. The calculator was still on & I tested the wire on the breaker and got 115 volts! A ups that was plugged into an outlet on that circuit was backfeeding the circuit through it's plug!

So, you never know what you might find!
Anybody got an Idea how that could happen?

Bill
Posted By: resqcapt19 Re: Power Quality Primer - 02/12/01 01:49 PM
Sparky,
Your original post stated:
All other circuits in the 120/208V 3 phase panel showed normal fluctuations in voltage and current. The voltage was steady on the questionable circuit on the line side of the breaker, but fluctuated as described above at the receptacles.

This appears to m to be nothing more serios than some type of poor connection somewhere between the panel and the loads.
Don(resqcapt19)
Posted By: sparky Re: Power Quality Primer - 02/13/01 12:46 AM
Bill,
the incident i mentioned was a stinky little UPS, cept' it was introducing a pulse on the circuit... probably built by the same satanic order

66'....what did you weed out there pal? We're all on the edge of our keyboards here... [Linked Image]
Posted By: sparky66wv Re: Power Quality Primer - 02/24/01 07:59 AM
Fluorescent lights under the counter on the opposite side of the 'puters. They were sharing the circuit. I'm not certain they were causing the flucuations, but they couldn't help. The circuit was also being shared with the office next door and was difficult to troubleshoot.

The dedicated circuit must have solved the crashing problems cause they've paid their bill!



[This message has been edited by sparky66wv (edited 02-24-2001).]
Posted By: tajoch Re: Power Quality Primer - 03/03/01 09:39 AM
Your place in question is next door to a doctors office? and they share a power panel? Dunno about ya'll, but my doc has his own X-ray machine, among other diagnostic items.....
One place I worked, Someone had placed a sign on one of the welders, 2 rooms away from the Maint supply guys desk, stateing, that if you needed to weld, you needed to inform him to shut down his computer. It was dated 10 years before i started working there. Well we started X-perimenting, and found out that they were both fed from the same panel, we also found out that the physical location didn't matter much, end result we re-wired the comps recept's to a panel on another X-Former solved the problem.....
Posted By: sparky66wv Re: Power Quality Primer - 03/03/01 03:10 PM
Said business is rebuilding and moving soon, so I didn't complain much about the setup.
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