When should an older UPS be replaced?

This is a question that virtually all IT and data centre managers will have to answer at some point. But the answer is not always self evident as it depends on several factors.

• The present UPS conditions and capabilities
• The future requirements and constraints

Most UPS manufacturers recommend a service life for their products of 10 years. Once a UPS has been in service for 10 years or so, the following three options present themselves to the owner:

1. Buy new – Should the UPS be replaced with a new one?
2. Upgrade – Can it be revitalized in some way to extend the life and performance for several more years?
3. Do nothing – Or is it better to do nothing beyond the most basic maintenance and just let it, in effect, “run-to-fail”?

Each option has their own set of advantages and disadvantages.

Conditions likely indicating the UPS must be replaced with a new one:

The first thing to determine, is whether the existing legacy UPS is (or soon will be) unable to meet its performance requirements and can it be feasibly serviced or upgraded to do so. If the answer to both of these questions is No, replacement with a new UPS is the recommended option in this case.

• Support and Spare parts are no longer available. Typically this occurs 10 years after model is phased out from production. Lack of support or parts makes routine maintenance & recovery from failure impractical, if not, impossible.
• Excessive maintenance costs
• Cannot meet critical performance requirements (supporting the entire IT load at the required redundancy and runtime levels), then it is at “end of life”, at least, for that application.

Is your current UPS costing you too much to run?

The efficiency of the UPS system, to a large extent, determines the operating cost. So it is important to understand how efficient the UPS system is today and how it can be improved through upgrades, changed load requirements, or by replacing with new UPS(s). Energy savings should be accounted for in the decision process.

• Internal design efficiency. Modern UPS systems operate in the 94%-99% range while older legacy UPSs are at 85% -92% across the same load range.
• Utilization rate. Generally speaking, efficiency is better at higher loads than lower. Modern UPSs typically maintain high efficiency levels even at loads as low as 50% or lower.
• Redundancy architecture. The facility’s design redundancy has a direct impact on the UPS’s utilization rate. A 2N design implies that each UPS would not be more than 40-50% loaded. If either UPS failed or went offline, the other “backup” UPS would be capable of carrying the rest of the load. This low utilization rate negatively impacts the facility’s power usage effectiveness (PUE). Particularly for an older transformer-based UPS, efficiency is significantly less at half load than at 90%, for example. Older transformer-based UPSs can have efficiencies in the 85% range when loaded at half load.

Is your current UPS capable of meeting your future needs?

How the IT load is expected to change over time should also influence the decision to keep, upgrade, or buy new.

If the existing UPS system is at or near full load and future load growth is anticipated, options to add capacity must be explored, such as adding more power modules or another UPS unit in a parallel system configuration, assuming the existing UPS system allows for it. Obviously, if the existing UPS capacity cannot be changed to meet the future requirements, then buying new is the only option.

Assuming the UPS is meeting the load and runtime requirements, you could choose to leave the old UPS in service and let it run to failure. But this would be a highly risky path to take.

Careful planning, close facilities/IT cooperation, and a well-trained operations team would be necessary to minimize the impact of the UPS’s imminent and inevitable failure. This could be an option if you are soon planning to outsource/move everything to cloud.

Understanding the current situation and future requirements will largely determine whether it makes more sense to “run to fail”, upgrade, or buy new.