In message <01111010365401.00989@burns>, burns <[EMAIL PROTECTED]> writes >Discussion at work yesterday: > >I had always been told that it was not a 'good thing' to place two power >elements in-line that have surge protection elements. Example: a rack-mounted >UPS system from which rack power distribution panels are fed that have their >own built-in surge protection. I was surprised to learn that some of our >architects had never heard of this. > >I know that there are some electronic engineering types on this list (Mike). >Can someone confirm whether or not this is true, or urban myth? And, if true, >what is the principle behind the problem and the potential consequences?
Amateur opinion. In normal operation, varistor surge protectors on the output of a UPS should have no effect. Nor is there any point in having them, and they add another point of failure. Having a surge protector on the output of another surge protector should have no effect. However, if a surge protector on the output of a UPS goes short circuit (which is unlikely except due to a fault) it could trigger the protection circuit in the UPS and cut supply to any other equipment on the same UPS. The same would apply to any short circuit fault in the equipment supplied, of course, the surge protector just adds another possible fault. It is unlikely any decent UPS would have such a distorted output waveform that the surge protector clipped it, but I suppose it is possible, and this would waste power and heat the surge protector, most unlikely to be high enough voltage to permanently affect it though. Conclusion, bad engineering, but not a major risk. I should be interested in other views. -- Roger Hayter _______________________________________________ Linux-users mailing list Archives, Digests, etc at http://linux.nf/mailman/listinfo/linux-users
