On Sun, Sep 29, 2013 at 11:06:14PM -0700, Dick Steffens wrote: > I have an APC Back-UPS ES 550 UPS.
Does the unplugged UPS provide enough power to start up the machine? That is probably an Offline/Standby UPS. In normal conditions, it feeds power straight from the wall to the load, bypassing the charger and battery and inverter. When the power goes down, it twiddles its thumbs for a missing cycle or two, fires up the inverter from the battery, throws a relay, and starts feeding the load, which has been without power for 30 milliseconds or more. The better UPS units send a signal over USB to the computer to signal "suspend NOW". As you can imagine, a computer with a just-barely-adequate power supply, accustomed to a squirt of power 120 times a second (plus and minus lobes of line frequency), might lose hope and die during a very brief interruption of those squirts. Inside the computer power supply are some electrolytic capacitors which may have been full value when the machine was new, but may have been cooked to weakness. Same electrolytic problem for the UPS itself, which may also have worn out batteries. And you may have added peripherals to the Gateway computer that draw down the power faster. A bigger third party power supply with larger internal capacitors might help. The UPSs that Really Work are "online" UPSs. Power from the line charges the battery, battery power drives the inverter continuously, which directly powers the computer. If the charger shuts down, the inverter and computer keep running until wall power comes back or the battery is exhausted. If everything is functional, zero power interruption. Of course, online UPSs are more expensive. Either the larger computer power supply, or the online UPS, will make heat continuously that the offline UPS and smaller computer power supply won't. You can spend Even More Money on high efficiency "green" power supplies and UPS units. There may even be computer power supplies that connect to 370V batteries directly, supplementing the electrolytics, which is more efficient still. This is what the big data centers are evolving to. The power grid is becoming more unstable and less reliable. Utilities are strapped for cash and required to absorb intermittent, unpredictable "green" energy. And your neighbors are buying plug electric cars - when their multikilowatt chargers turn on, the line power will sag a little (or a lot, depending on charger design). And if climate change expands the Hadley cell and moves more tropical storms north, we will have more wind and rain storms at 45N. And we won't have as much glacial melt to power hydro in the summer and fall. So a good offline UPS may be needed for the power grid of the future. Encouraging versions of the Linux kernel that can recover from instant power loss might be called for, too. Spotty power availability is the norm for most of the world, and most future computer users. We should help build software for the precarious power world, and for our own future as we reduce our own industrial capabilities. Keith -- Keith Lofstrom [email protected] _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
