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We have a small datacenter with seven APC 5000VA rackmount UPS. These have had regular battery replacement, but have just passed 10 years of service. We also have a boxed spare unit of the same model in storage.

The devices have seen very few outages or power events over the 10-year period, perhaps 2 total outages and 15 under-volt incidents over 10 years.

I need to decide if it is time to budget for replacing these UPS, which I would like to delay as long as possible as the replacement cost will be in excess of $35000 USD.

How long should the electronics/relays/etc in an line-interactive UPS last? Are there any safety issues, such as increased fire risk from aging electronics? I have heard of capacitor-failure-induced fires in UPS units, but those were from long ago and involved on-line UPS. These are line-interactive units, so the high-power electronics should be seeing no load 99.9% of the time, correct?.

The manufacturer of course suggests capacitors only last “up to 10 years”, but that seems to be a biased source.

We have replaced all the batteries 3 times over 10 years and everything seems to be working fine.

The UPS all still pass their weekly self-tests, which include a switch to battery for several minutes to measure voltages and runtime.

All of our severs and switch pairs are connected to at least two different UPS, so losing one unit to failure will not impact availability, and as I mentioned we have a stocked spare.

APC even still sells the exact same model of UPS as new.

Looking for informed experience from DC operators.

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How long should the electronics/relays/etc in an line-interactive UPS last?

You will find it difficult to get an answer to this question because it depends on too many factors. Quality of components used in the UPS, the quality of the manufacturing process, shipping/storage between factory and consumer, handling during installation, environment differences (temperature, airflow, input power quality, etc), and the load generated by the equipment connected to the UPS are just some of the factors that would affect this answer. Any of these factors can vary even between units produced at the same time.

If you ever get someone to give you a clear answer to this question, make sure to check for the fine print. It will likely use some sort of predictive method based on the system design rather than actual data. By the time enough actual data is collected to calculate an accurate lifespan for a UPS model, it will likely have been out of production for some time.

Are there any safety issues, such as increased fire risk from aging electronics?

It would be more accurate to say that there is an increased risk of failure as electronics age, and that failure can potentially result in a fire. However, most failures will not result in a fire.

The exact nature of that failure will be determined by which component(s) fails and for what reason. I have had electronics (both old and new) where components short/burn, ones that simply stop working/fail self tests, and others that start acting "strange" or inconsistently. I personally have yet to see any electronics I am working with fail in a way that starts a larger fire, but the potential does exist.

These are line-interactive units, so the high-power electronics should be seeing no load 99.9% of the time, correct?

Incorrect. When running on AC input power, a line interactive UPS uses almost all of its electrical components; it will use less of them when on DC battery power. Most of the electronics are used for filtering and/or detecting problems with the AC input power. When AC power is present, it still runs through the inverter to both maintain battery charge and provide output power. Power from battery through the inverter is generally considered "clean" and is typically not filtered.

I need to decide if it is time to budget for replacing these UPS, which I would like to delay as long as possible as the replacement cost will be in excess of $35000 USD.

I think this is the heart of your question, even though it isn't phrased as a question. It indicates that your company lacks a replacement schedule/plan/policy for your IT equipment, and every business should have one.

Replacement plans are often driven by one of two types of policy (which may vary depending on type of equipment). Many businesses follow a time based policy. In your case, this could be something like "UPSes are replaced every 8 years." Often this type of policy will be "rolling" in some way (i.e. replace one quarter of the units every other year). Others companies will base their policy on some sort of performance metric. For this example, it may be something along the lines of "we will replace all of the UPSes within two years after product end of life or the first one fails outside of warranty."

The advantage for time based policies is they are simpler for long range planning/budgeting and can help reduce the risk of unplanned downtime due to equipment failure. The trade off is that they tend to have higher capital costs, as you are clearly aware by your statement.

Once your company has a replacement plan, it should make it fairly easy for you to decide when you need to budget the replacement.

  • For what it’s worth, the company has a replacement plan for almost all our hardware. The UPS chassis (not batteries) were overlooked in previous plans/budgets and we’ve been asked to not spend the money now if practical. – rmalayter Aug 31 '18 at 2:01
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    @rmalayter, my choice would probably be a rolling upgrade. Do two (or more) a year starting as soon as you can work it into the budget. Start with the racks that have the most mission critical servers. This will give you more spare units (btw, get the spare out of the box and powered on) in case of failure. Once you have these units replaced, you can implement any replacement plan you want. – YLearn Aug 31 '18 at 4:17

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