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UPS Pro 550 strange behaviour when off and slave not voltage free

APC UPS for Home and Office Forum

Schneider Electric support forum for our APC offers including Home Office UPS, Surge Protectors, UTS, software and services and associated products designed to share knowledge, installation, and configuration.

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UPS Pro 550 strange behaviour when off and slave not voltage free

This question was originally posted by Malte on APC forums on 1/21/2016

Hi there,

I just purchased a new Back-UPS Pro 550 and it shows some strange behaviour.

First, I defined a master device, a PC and set a limit when the device is supposed to be powered down from view of the UPS.

But, when the master is off, the slave outlet is not voltage free! My USB hub still had the LED on and so I measured the voltage. I saw, the slave still had around 0,2 to 0,6 volts. Is this normal for the slave?

Even when I shut down the UPS, the slave still has this voltage. The master is voltage free as expected.

Second, when the UPS is off, but still connected to the wall outlet, every 10, 20 or 30 seconds the three buttons on the UPS flash for the fraction of a second and a very, very short beep occurs, again a fraction of a second.

Besides that, the UPS works as expected. It correctly shows the power consumption of connected devices and battery backup works fine when I pull the main outlet of the UPS.

But this strange behaviour of the slave outlet and when the UPS is off makes me wonder, whether this is normal behaviour for this device or if there is any reason to replace that device....