On Apr 29, 2:07 pm, Anne Brataas <[email protected]> wrote: > More thanks to more folk for insight into power issues! I so > appreciate your experience and knowledge and willingness to share it!
I would love to hear what these people are seeing on their oscilloscopes. Because that is not the waveforms I observe. As Clark Martin said, > Most UPSes produce what is called a modified sine wave and > it is about as ugly as power gets. How ugly? It can even harm small electric motors. For example, this 120 volt UPS outputs two 200 volts square waves with a spike of up to 270 volts between those square waves. Others called that conditioned power? Well yes, when that is the popular myth and when nobody bothers to provide technical specs. It should bother you that the majority say one thing, but those who actually do this stuff (even look at those waveforms on an oscilloscope) are so few and say something different. When not in battery backup mode, a computer grade UPS connects a computer directly to AC mains. This is when power is 'cleanest'. Why is it called a computer grade UPS? Computer power supplies are so robust as to make even poorest power irrelevant. Power so 'dirty' as to even harm small electric motors and power strip protectors is completely normal and acceptable to a computer power supply. So it is only sufficient as a computer grade UPS. Computer power supply even makes ‘dirty’ UPS power irrelevant. So what protects a UPS internal computer circuits? It also needs a power supply equivalent to what is standard in all computers so that the UPS is also not damage. If AC power is so harmful to a computer, the same power is also destroying the UPS. Mnay if not most who recommend UPSes don’t know any of this; but have heard many popular urban myths. Where is the manufacturer numeric spec that states what others have claimed? Its only purpose is to protect data from blackouts and extremist brownouts. How extreme? Computers must even startup and work normally when incandescent bulbs dim to less than 50% intensity. Another function standard in computer supplies; because computer supplies are required to be that robust. What must your computer be protected from? Blackouts and brownouts can harm data; not hardware. Harmonics, noise, and surges require other solutions. To be deceived, others will assumes all electrical anomalies are same. All are solved by one magic box. It does not work that way. Different anomalies require different solutions. Why do I know this. Whose tasks require using an oscilloscope? And who read those manufacturer specs before posting above facts and numbers? As Clark Martin said, > Most UPSes produce what is called a modified sine wave and > it is about as ugly as power gets. That means a UPS in battery backup mode may even degrade or be damaged by a connected strip protector. That is why laser printers with electric motors are best not connected to the UPS. Buy a UPS for the one function it really claims to do: provide backup power during blackouts so that data can be saved. Also buy a UPS with more power than you require because its batteries degrade quickly; often within three years if the UPS is only just powerful enough. And appreciate that only a minority actually provided numbers for that so called ‘conditioned’ UPS power. A spike of up to 270 volts is about as ugly as it gets. That spike must not harm any computer because protection already inside every computer is that robust. So what do you really need to protect from? --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
