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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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In Reply to: Re: Soundmind: I need guidance on assessing risk. posted by Lynn on July 6, 2006 at 19:38:20:
" Of course, with the AC running in 100+ temps (May-September) the lights do dim every 20 minutes but that is another story."When air conditioning compressors and other large motors first start up (for a compressor each time it is called on by the thermostat to supply cooling), they draw a great deal of current called "inrush current" for a brief moment. This usually pulls the voltage down to all other loads connected to the same transformer. (This can be minimized by greatly oversizing transformers and feeders in the design when necessary but for residential construction would be an unacceptable extravagance to a utility.) The regulation of a UPS will reduce this effect to where is has little or no significance. When you buy one, try it by connecting one table lamp to it and have another nearby not connected to it. When a compressor starts, the one on the UPS should dim much less if at all.
I noticed at the bottom of the web page I cited, there are links to MGE and Liebert as well. IMO these are the main competitors for Exide Powerware for high quality UPSs. But there are many other brands and some of those are high quality too. APC is the largest manufacturer but they have concentrated in the past mostly on small units for PCs. Understand that my involvement is usually with much larger equipment. The manufacturers of this big equipment have extended their product lines downward trying to capture for them what is in aggregate potentially a large lucrative market. They bring the same high degree of engineering expertise and quality build standards they must consistantly demonstrate to maintain the confidence of their users of large machines. Some of the manufacturers of smaller units would like to get into the bigger machine market but when your job is on the line, you don't buy what you don't already trust unless you are forced to engage in very open bidding by your purchasing department. If I have a job where I need to bid three suppliers, these are the three I pick and I don't care which of them wins. But forced to use someone else I haven't dealt with extensively and don't have good references for and I become concerned. Some of them quite frankly can be a PITA and so can the distributors. (OK, I admit that with the exception of MGE, I've had at least one good knock down drag out fight with practically every major UPS manufacturer I've ever dealt with and I was glad when Topaz disappeared off the face of the electrical world.) Usually, small units for PCs and peripherals are supplied by each department buying them from places like Staples, Office Depot, various mail order houses, who knows maybe even circuit city, and I don't get involved. Lots of times, a purchasing department will just get a spec and go shopping. Keeps them off the streets and out of trouble. Even a 5 KVA machine for me is only for some very small project, maybe to back up a control panel for some special application or a small piece of lab gear. For PCs, almost any of them will do but for more critical audio equipment applications where rf noise could be a problem, I'd stick with these better brands even though they are probably more expensive. They are usually not sold at common retailers but must be bought through electrical supply houses. Their web sites should have a list of local sources. They also have very extensive applications engineering departments who should be able to give you all the personal help over the phone you want for picking the most suitable of their products for your application. Each one will undoubtedly tell you why compared to his competitors alternative, his employer's unit is the best but of course that should come as no surprise.
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- Re: Soundmind: I need guidance on assessing risk. - Soundmind 20:48:25 07/06/06 (0)
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