ECN Forum Forums Code Related Discussion NEC & other Code issues Power Quality Primer

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).]

A good fundamental bookmark Joe !

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...

66', so how did the pharmacy make out??

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...

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...

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....

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.

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...

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.