In the last few years I’ve noticed confusion cropping up about what the term “modular” really means when it comes to a 3-phase uninterruptible power supply (UPS). By my count, there are now at least 16 different 3-phase UPS platforms claiming to be modular. But as is so often the case with IT and data center infrastructure, the word doesn’t always mean the same thing when applied by different vendors.
So in this post, I’ll offer up four questions you can ask your UPS vendor to determine the extent to which its 3-phase offering truly is modular, and whether the offering addresses the need that you have in mind for it.
- Which UPS components are modular?
First up is to determine which components really are modular. In many cases, you’ll find the vendors offer only modular power. That’s good if all you need is, say, N+1 redundancy to protect IT loads or other critical equipment. It means you can have multiple power blocks such that if one fails, another can protect your load. That’s certainly valuable, but it addresses only that specific pain point. If that’s the only component that’s modular, it also means you’re sacrificing lots of redundancy, which leads to our next question.
- Which components are redundant?
While it’s great to have redundant power modules, for critical loads you may well want redundancy in several other components, including:
- System level controller, which is the brains of the UPS. If the UPS has a modular system level controller, then you can achieve redundancy at that level as well.
- Power supply unit, which converts mains power into internal power; N+1 redundancy here is likewise a good idea.
- Battery strings: modularity here allows you to have two, three, four or more battery strings, as the level of required redundancy dictates.
- To what extent can I scale the system?
Having numerous modular components also enables you to more easily scale the UPS either up or down as demand warrants. That means you can take a “pay as you grow” approach. Perhaps you start with one power module, two or three power distribution units (PDUs) and one string of batteries. If your load doubles, you can add another power module, battery string and PDU – and on and on. From a total cost of ownership perspective, that approach makes far more sense than buying a UPS that’s larger than you need from day one to account for future growth.
Similarly, if you conduct a data center consolidation project or move some resources to the cloud, your UPS requirements may be reduced. Modularity also makes it simple to remove components, so you’re not paying to operate a UPS that’s larger than you need.
- How do I deal with component failures?
Another money and time-saving aspect of truly modular UPSs is that they are simple to service. If the only modular component in a UPS is the power module, customers may think if one fails they simply replace it with another and they’re back up and running in no time. But it’s often more complicated than that. There’s a process to follow to program the proper addressing of the new power module such that it’s recognized by the UPS, which takes time.
In a truly modular UPS, the new power block will be instantly recognized by the system and literally ready to work in minutes, with no need for complex addressing or power on procedures.
Similarly, if components such as the system level controller, power supply, batteries and PDUs are modular, they too are far more easily replaced; there’s no need to take down the entire UPS system, nor to turn it off. That can be invaluable in situations where down time is simply not acceptable.
To get a sense for how all of these modular components come together in a single chassis, check out this video of the Schneider Electric Symmetra PX. It does a nice job of showing what Schneider Electric means when we talk about a modular 3-phase UPS – and it may be quite different from what you hear elsewhere.