UPS help!

[audiocableguy]

Hello, Not sure where to use a single large UPS or multiple units. The brand is Powerware and all the units are the online type.

I have found a few articles saying that if one were to extend the output of a UPS unit beyond 25ft. noise would re-enter the line and the output isolation x-former would be useless. Would conductors installed in EMT help to reduce this noise? Would wire insulation type be a factor?

The second part: If I were to install 6 seperate single phase UPS units would the harmonic problems cause more problems than the noise entering the wire in the above senario? Also, If the UPS units are seperated in different rooms and the equipment is tied through signal grounds and coax shields would the differences in inverters or conditions cause concern?

Any suggestions or ideas welcomed!

 

[dereckbc]

Re: UPS help!

Originally posted by audiocableguy:
I have found a few articles saying that if one were to extend the output of a UPS unit beyond 25ft. noise would re-enter the line and the output isolation x-former would be useless. Would conductors installed in EMT help to reduce this noise? Would wire insulation type be a factor?

Distance is no factor other than voltage drop. EMT does form a EMI/RFI shield. Wire insulation does not have much effect at power/safety frequency ranges. Stick with THHN or what ever insulation you prefer.

 

[dereckbc]

Re: UPS help!

Originally posted by audiocableguy:
The second part: If I were to install 6 seperate single phase UPS units would the harmonic problems cause more problems than the noise entering the wire in the above senario? Also, If the UPS units are seperated in different rooms and the equipment is tied through signal grounds and coax shields would the differences in inverters or conditions cause concern?

Only upstream of the UPS units if they are single phase, but it is greatly exaggerated. I prefer to use a centrally located 3-phase UPS to minimize harmonics and loading problems.

More and more data centers are popping up and trying to cut facility cost by only providing commercial AC power with a stand-by generator as back up power and eliminating the UPS cost, thereby putting the cost of the UPS on the customers back. Again it is a design issue.

EGC's are not suitable as a signal ground. Therefore if a signal ground network is needed it should be provided in the form of a SRG or other suitable form. Modern signal techniques do not require a signal reference such as optical, e-net or other balanced transmission mediums.

[ October 26, 2003, 08:43 PM: Message edited by: dereckbc ]

 

[crash]

Re: UPS help!

I am not an expert on ups systems so please take my opinions with a grain of salt. The purpose behind a ups is to provide a "perfect" ( as close to possible as perfect ) 120 Volt sine wave (uninterrupted, should power fail), power source to sensitive electronic equipment. Since this definition necessitates that the ups "remove from the line" any harmonics that are generated by other equipment in the system, I would assume that a ups of sufficient quality would be able to be installed in a building that has other ups's and other electronic equipment. Five other pieces of electronic equipment does not to me sound like a problem, but, "what? is already existing in the building?" , you have not mentioned this! As for the distance of 25ft, it sounds suspiciously short, I know that I can plug my computer into a 25ft extension cord (plugged into a non ups source) and not have a problem, however if I had a couple of 240HP 4.16Kv motors operating in the same room, I do not believe the same to be true. I would think that "common sense" would give you your best opportunity for success in this installation. My "opinions" on your questions are: yes, no, no, maybe ( the answer to the last, being based on "coax").

 

[Guest]

Re: UPS help!

Cheap, consumer-level UPS's use "Approximation of Sine-Wave (AoSW)" which can harm computer equipment (according to the mfg's of computer equipment). APC and others that sell low-end stuff will play dumb if you ask them about this issue. Some mfg's will not honor their warranty (or they will try to not honor it) if you admit to have an AoSW UPS.

Fortunately, audiocableguy is in the upper echelon of UPS usage and won't be dealing with AoSW.

Of course, APC and others have high end UPS models that are suitable for power conditioning. They also have Automatic Voltage Regulators, etc. for power line conditioning.

I still consider myself green on this subject, but I have researched it, implemented it, and attended several mfg sponsored seminars (in person & online) on it (and passed some in person & online tests). I read everything I can here about this topic, and I try to assimilate for future implementation. Short of getting an EE I want to be as up to speed as possible on UPS & power conditioning. I bow to Dereck & the others here that understand this stuff at the board level.

I have witnessed power conditioning do magical things to buggy computers & buggy electronic equipment.

 

[ron]

Re: UPS help!

When you say "a single large UPS or multiple units", are asking about multiple single modules distributed throughout the facility, or a multi module system located in the same general area offing redundancy to each other?
There are many options, and many scenarios which might make one method better than the other.

The best place to start is with equipment that has dual power supplies. Then bring two different circuits from two different UPS's to that rack. Redundancy is the key for reliability.

 

[brian john]

Re: UPS help!

NOT TRYING TO BE CRITICAL OF YOUR RESPONSE BUT>>>>>>>>>>>>>>

I am not an expert on ups systems so please take my opinions with a grain of salt. The purpose behind a ups is to provide a "perfect" ( as close to possible as perfect ) 120 Volt sine wave (uninterrupted, should power fail), power source to sensitive electronic equipment.

NOT TRUE the sine wave is not perfect.


Since this definition necessitates that the ups "remove from the line" any harmonics that are generated by other equipment in the system, I would assume that a ups of sufficient quality would be able to be installed in a building that has other ups's and other electronic equipment.


NOT TRUE unless ordered with harmonic input filters (line side). Load side depends upon the harmoinics generated by the load.

Five other pieces of electronic equipment does not to me sound like a problem, but, "what? is already existing in the building?" , you have not mentioned this! As for the distance of 25ft, it sounds suspiciously short, I know that I can plug my computer into a 25ft extension cord (plugged into a non ups source)

DEPENDS ON WHAT 5 PIECES OF EQUIPMENT AND HOW SENISTIVE THEY ARE.

 

[DaveTap]

Re: UPS help!

Audiocableguy what are you trying to power with UPS? I have a lot of background with audio, video and lighting systems from studios to outdoor concerts as well as some solar power/inverter experience. Audio and Video equipment only use AC to create the DC voltages required. The AC required is usually not critical (provded it can produce a stable DC voltage)and on most equipment is filtered to prevent "noise" from reaching the secondary DC ciruits which are usually also filtered. For that reason probably the most important concern is voltage drop and although 25 feet has never been a problem 250 feet could be, but it would be the exact same problem coming from the POCO or a generator. We try to isolate our lighting equipment from our audio and video gear because the SCRs and Triacs generate a lot of noise... hard switching at 60hz... which of course is audible. Our experience has been it works fine to install a UPS at each required location (usually in the same cabinet or case as the equipment) as opposed to one large unit powering multiple pieces of equipment, not to mention being cheaper and easier because of the extra distribution required for a central unit. That being said there are often still problems from harmonics in mic cords, etc. that can be challenging to solve, but that why you make the big bucks right?

 

[CharlesC10]

Re: UPS help!

UPS's are a complicated topic. I worked at a large plant (many large motors and big welding shop) several years ago that had just installed a new WindowsNT server with many networked terminals. The IT guy started having many HD crashes. The company sent me to two classes at this web site: www.powercet.com. Not cheap but incredibly valuable. Many of the students came from POCO's. One of the classes is Uninterruptible Power Systems: Problems and Solutions. We could have hired this company to track down the PQ problems ($$$) but we first tried UPS's, APC's Smart-UPS, at many locations in the plant. Cured all of the problems. I then installed them on the ph. system and alarm system. I have also installed UPS's on gate access control systems, both the motors and the elecronics, up to 150' in distance with no problems. I have them on my home and office computers and my cordless ph. system. Never a problem. I only have experience with APC as they were the biggest player at the time and their warranty and tech support was the best. (I don't own any stock.)

I know there are big differences between the types of UPS's from one manufacturer to another. I would suspect that any of them can inject noise into an audio systems so I would be careful about that application. Just plan on replacing the batteries about every 3.5 years, not cheap. More electricians should try and sell these products to their customers.