The Local User Has Fallen Outside the Limits

From the user manual for my new uninterruptable power supply:

The UPS operates on battery when the line voltage or frequency has fallen outside the limits. Local users are alerted to this mode of operation by visual and audible indicators. The UPS provides power to the load from the battery and through its inverter and the output voltage and frequency of the UPS are regulated within a narrow band.

Enticed by a lower price (by about 40%), I opted to pass up the reliable APC and Belkin brands and take a gamble on the MasterPower UPS 525VA. My favorite feature so far is on/off switch: you have to hold down a button for a full three seconds, during which the UPS emits a loud, piercing, continuous beep and displays a cryptic green light. You turn it off the same way. Unfortunately, to figure this out you have to read through a couple pages of instructions like the ones quoted above (all in tiny print) until you get to a buried little sentence that tells you the secret of turning it on.

It was hard for me to guess this secret technique because as soon as I took the UPS out of the box, plugged it in, and tried pressing what looked like the on/off button it would immediately emit that load, sharp, continuous beep. My instinctive reaction was to stop pushing the button as quickly as possible to stop the horrible sound. It never occurred to me that I had to suffer through a full three seconds of the beep before the UPS would come on.

Before I could find out the secret to the on/off switch, I had to read through, among other things, an explanation of how I, as the "local user," could "determine the load" by calcuating the sum of all of the "V x A ratings." It is apparently essential to do this before plugging anything into it. I was also treated to the explanation I quoted above. There is also a nice block diagram of the internal electronics of the UPS, and some nice diagrams of French, German, and British electrical outlets. I bought my grandmother one of these things!

This UPS is only 300 watts, but I really only need battery backup for my CPU for the momentary blink-out power outages. As long as the auto-shutdown software works, it does not matter to me whether or not I have five minutes of backup or thirty. Other than the fun I've had with the on/off switch and the user manual, so far I'm a happy customer. Despite its awkward interface and bad user manual (truly, it is an unintentional work of art), the UPS appears to be well constructed. I'm glad, though, that I bought my grandmother the APC, which has very nice, friendly instructions.

Dan