Modular UPS configurations offer both immediate and long term benefits

Users purchase UPS systems to protect their equipment from power failures and mains disturbances. The most cost effective solution in each case depends on several key aspects of their installation - its current size, expected future expansion, and the criticality of system availability.

In low-end power applications of up to 10kVA a standalone UPS configuration is usually most suitable, being the simplest and lowest cost. Users with power requirements in this range usually have limited budgets for UPS protection. Also the availability offered by a standalone system is sufficient for the critical demand of their application.

Above 10kVA, priorities start to change. Protection of the load becomes critical, with the consequential cost of failure climbing to many times the UPS equipment cost. Redundant parallel UPS systems with higher availability become essential. If one UPS unit fails, another can support the critical load without interruption or transferring to the raw mains supply.

Redundant higher availability systems are often configured using conventional standalone UPSs connected in parallel. These configurations suffer the disadvantages of larger size, higher weight, more losses and longer MTTR. A modular UPS configuration is a far more efficient solution, with parallel redundant modules contained within a single compact cabinet. The smaller size of the modules allows efficient matching of the UPS capacity to the load size and the redundancy level required. If one module does fail, it can be hot swapped very quickly. This minimises time to repair which in turn significantly improves availability.

Even in situations where a standalone UPS appears to be the simplest and cheapest solution, a modular configuration with a higher initial cost could actually be more cost effective in the long term. If over time the critical load grows beyond the original UPS capacity, a standalone system would have to be removed and replaced by a larger capacity unit - an inefficient and expensive exercise. By contrast, a modular UPS could be upgraded relatively easily and cheaply, by simply adding a module to the existing cabinet. In a hot swap system, this upgrade could be implemented with no downtime at all.