Answer: A modular UPS is an uninterruptible power supply built from multiple hot-swappable power modules that operate together as one scalable, redundant system. Unlike a traditional monolithic UPS, it lets you expand capacity and add redundancy (N+X) by adding modules, and service a faulty module without shutting down the load.
How it is built
A modular UPS has a common static switch / bypass cabinet and a rack of identical power modules. Capacity is the sum of installed modules; redundancy is the number of spares (N+X).
Why it matters
Because modules are hot-swappable, a failure or upgrade does not take the load offline. Capacity can grow with the site instead of being oversized up front.
Common use cases
Data centres, industrial plants, healthcare and anywhere load grows over time or where downtime for maintenance is unacceptable.
Where to go next
Compare it directly with a single-unit design in our modular vs monolithic UPS guide, and see IWAY industrial UPS systems.