APC Back-UPS is slow to respond to power disturbance

[jjuly_apc]

APC Back-UPS BE550G is slow to respond to power disturbance.
My computer shuts down but other devices such as
the cable modem and router continue to operate.

I am not using any power management software.

purchased Sept 2012

Looking for advise on how to proceed. I am in Panama, so bringing it to the shop is not feasible.

Computer: PC with Win7 ultimate. Power supply was replaced, but the problem persists.

John

[BillP]

silly question but did you verify the computer is plugged into a battery back up + surge outlet and not just surge only? also, you said the computer shuts down - i just want to make sure it turns off and stays off versus reboots.

depending on the answers there, your power supply maybe is too high end for this type of UPS. you may need to look into a pure sinewave UPS which generally also have a quicker transfer time to battery. that is what usually causes this type of thing assuming the computer is plugged into a battery back up outlet.

[BillP]

Some computer power supplies have longer "hold time", i.e., greater storage capacity that would get you through the Back-UPS transition time.  I know you said you replaced the power supply, but it may be worth a shot at a very high quality (more expensive) power supply from a reputable vendor.  Also, even though your computer seems to work fine with, let's say, a 450 watt power supply, installing an extremely robust 1kw or 1.2kw power supply (again from a reputable vendor) would add to your computer system's "hold time" and may get you through the transition from commercial to backup power.

[BillP · Accepted solution]

You've indicated the UPS shuts down your computer. Can you verify this is a complete power off of the computer or does it reboot, powering back up to the login screen?

A complete power off would suggest a possible incompatibility between your CPU power supply and the step approximated sinewave output of the UPS. A reboot, would indicate an issue of the CPU power supplies ability to support itself during the long transfer of the UPS, from Online to Onbattery. This transfer time can be reduced slightly by adjusting the Sensitivity of this unit through PCPE or through the front display, whose process is outlined in the users manual. You may have better results once this Sensitivity has been adjusted to it's highest setting.