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#68302 - 08/02/06 10:16 AM Power Quality  
mshaw  Offline
Member
Joined: Jan 2006
Posts: 44
Fairborn, Oh, USA
I am having issues with one of my buildings. I have several tenants with large server rooms with large UPS systems which record power quality issues. They also have lots of individual pc units that are not on ups. There are experiencing power drops about 3-5 time a month. Some drops are severe enough to cause the non ups protected computers to reboot loosing data. All events are loged by the data center ups's Had the local power company do a power quality survey on the building for 3 weeks and we were able to identify several incidents attributable to power grid issues,faults and cap bank switching. We compaired the monitor results to the UPS logs and discovered that some incidents could not attributed to to the power grid and could indicate possiable faulting on the secondary side. Shutting down a building of this size with the various data centers will be a nightmare in order to meger the secoundarys. Any ideas ! 1200 amp 480 feed existing secoundarys are about 20 years old.


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#68303 - 08/02/06 12:35 PM Re: Power Quality  
feather  Offline
Member
Joined: Feb 2006
Posts: 25
Santa Maria CA USA
What about your other tenants? Any body running a VFD, Softstart, or DC drive? You might consider renting your own power monitor. Record the fault occurance time and check for repeating cycles. Chuck


#68304 - 08/02/06 12:47 PM Re: Power Quality  
Ron  Offline
Member
Joined: Mar 2002
Posts: 582
White Plains, NY
Lots of possibilities.
It is very possible that there are transients caused internal to the building. Are there TVSS' installed throughout?
Are the problems sags or swells or ....
It is a specialty to be able to interpret disturbance type meters and see from the oscilloscope plots, where and what the problems are, and where they come from.


Ron

#68305 - 08/02/06 02:08 PM Re: Power Quality  
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
Do you submeter power within your building? Try monitoring the subpanels to discover if power issues are being generated within the building or external.

1200 amp 480 feed existing secoundarys are about 20 years old. What shape is the grounding system in? Has anybody done a thorough review of the building system? Checking for tight connections, improper neutral ground connections, overheating conductors and panel boards, etc.

Are the HVAC loads on seperate panels than the UPS? Are there other large infrequently operated motor loads? Such as elevators, winches, fire pumps, air compressors, dumpster compactors, etc.

Fluke made a plug in 120V power monitoring system that could be read with an optical probe. I believe multiple data recorders could all be read with the same probe and software. Synchronise a handful of these and scatter them across the building loads.
Fluke VR101
http://us.fluke.com/usen/products/Fluke+VR101S.htm?catalog_name=FlukeUnitedStates

Edit to add website and model #

LarryC

[This message has been edited by LarryC (edited 08-02-2006).]


#68306 - 08/02/06 03:24 PM Re: Power Quality  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
Mike,

Where did the POCO measure this data? Was it at the secondarys of thier transformer, or at the service entrance?

Where are the UPS's in realtion to the service entrance, and are they on the 480, or are they on a 208 transformer?


#68307 - 08/02/06 03:30 PM Re: Power Quality  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
Larry, ever seen the electro-industries Shark 100 series?

They are a wireless,, real time power quality meter.

You can put them on every panel, and look at all the data from all the panels in real time.


#68308 - 08/02/06 09:49 PM Re: Power Quality  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
If it helps...here's a story...

A customer of mine had assorted power quality problems. I worked in the building for over a year, doing other jobs, when one Thanksgiving half the surge supressors fried, and the local UPS's kicked in. (Walking into the place was like entering a cricket convention.... chirp...chirp...).

While checking the assorted panels, trying to discover the cause, my partner was smart enough to back away, relax, and look at it all from a new perspective. Something just didn't seem right. After much headscratching, he noticed the "obvious;" ther was NO neutral wire! That's right, the panel was fed from a panel next to it, and the neutral bus was bonded to the case. 20 years of rust and vibration had finally loosened a locknut.

We ran a proper neutral, and a ground wire, removed that green screw... and the building now had amazingly "clean" power!

So- the 'moral' is... before getting into all sorts of fancy theories, check your basics. Just maybe, someone got careless....


#68309 - 08/03/06 11:00 AM Re: Power Quality  
mshaw  Offline
Member
Joined: Jan 2006
Posts: 44
Fairborn, Oh, USA
No VFD in building UPS are on disconnects straight off main buss bars monitoring was done on the secondary side of the transformer at the CT's All recording UPS are 480 feed. How do I determine if I am having transient faults in my secoundary feeds to my mains without a massive shut down and meggering? Some issues we are seeing are not related to power quality from the grid. Grounding for the UPS is up to code and has been evaluated as well as building ground.


#68310 - 08/03/06 07:13 PM Re: Power Quality  
Dnkldorf  Offline
Member
Joined: Dec 2004
Posts: 1,064
nowhere usa
Mike, I don't how much help this will be, but I think you'll have to do some logging.

Have you done any measuring of the system yet?

Can you email me a diagram of what you got, and where you measured?

I am curious of how you measured this problem as being a transient problem, as opposed to a dip,swell, and so on.

You can rent equipment to log this stuff if you have to, and then contact one of your suppliers. I would think they have application engineers who can help you solve this...Eaton does this..


#68311 - 08/03/06 07:24 PM Re: Power Quality  
LK  Offline
Member
Joined: Jan 2003
Posts: 1,429
New Jersey
"he noticed the "obvious;" ther was NO neutral wire! That's right, the panel was fed from a panel next to it, and the neutral bus was bonded to the case. 20 years of rust and vibration had finally loosened a locknut."

High rise office building, we found the obvious and changed out some of the floor transformers to copper, after that there was never a problem.


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