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How To Choose An Uninterruptible Power Supply?

I have an iMac (mid 2015 27″ iMac) and I use a UPS. Lately, I have had several instances where the line power failed (brown out) and the UPS switched to battery power. In spite of that, my iMac shut down. For a while it was quite a mystery and I even had Apple care technicians do a check. Now I have learned that the UPS I use is not suitable for my iMac and other PCs and such because of the way new devices use “power factor correction” (term I got from the maker of my UPS). Can you advise on selection of UPS for iMacs?
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Mike W

Comments: 3 Responses to “How To Choose An Uninterruptible Power Supply?”

    7 months ago

    Which UPS do you have? I’ve never heard of “power factor correction.” I have used a variety of UPSes over the years and never had an issue. So perhaps it is something rare? Most UPSes, after all, are made to be used in exactly this situation, to keep a desktop computer going.

    So perhaps this is just a matter of the UPS you bought not being up to the task of keeping a computer running. I can’t say much without knowing which one you had.

    I would just read the descriptions carefully when getting a new UPS and make sure that you get one built for keeping an iMac-like computer running. Maybe look at the reviews too and see if anyone reported a problem.

    Mike W
    7 months ago

    The UPS is an APC 650. I’ve come to learn the model has a feature that will cause the APC to shut down after 15 minutes if the power needs are low (15 watts and below). So, if the iMac is asleep, the APC will shut off and iMac shut off. The term power factor correction relates to the need to have a larger APC device because of the way PCs start up (power usage). That’s my extent of knowledge. In effect, I am lead to believe by APC I need their more feature packed UPS…read that as expensive.

    7 months ago

    Mike: 15 minutes is definitely more than I would expect out of a UPS. I would only expect a consumer-level UPS to help with power outages of a few seconds (common in some areas) and then if power really goes out, to provide just a few minutes of power so you can save your work and shut down gracefully. It may be able to handle 5-15 minutes, but I would never push it.

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