Modular UPS Systems Versus Standalone UPS Systems

Snowballing power requirements, improved component technology along with increasing user demand over the past five years have now driven modular UPS systems to be designed, specified, and supplied by all the leading UPS manufacturers.

Is my UPS really standalone?

Many “standalone” UPS systems, also referred to as “monolithic” or “solid state” by vendors are actually made up of internal components set out in a modular layout. Some manufacturers contain a number of physical modules with a single display and control screen with one covering front door, others have the internal components set out in a number of smaller power ratings which are then connected in parallel. One of the reasons for this is now the sheer scale volume in production of smaller switching semiconductor components compared to the lower number of larger semiconductor components. The vast scale of production means using three or four times the number of components is still more cost effective than using larger semiconductor devices. The components can also be set out more efficiently for heat dissipation saving physical space and increasing power density of the unit. It also reduces production time for the UPS manufacturer as only a limited number of power ratings need to be sourced and stocked. Therefore, You may find that your standalone UPS is actually of internal modular design and construction anyway.

Low Loading Efficiency

When a UPS is first specified, it is nigh on impossible for a user to know the total loading throughout the UPS service life, especially where the UPS supports a growing infrastructure company such as a colocation datacentre. Even when the load is accurately calculated and achieved, a “safety” factor is added to the load in order to to size the UPS in event of of any overload conditions, future server upgrades or unbalanced deployment of load across the output phases.

Like any electrical device a UPS would usually be most efficient operating at 100%, but this is neither practical nor possible in reality. While standalone UPS have been optimised to provide high efficiencies at mid loadings, the user will have to choose between future power availability or maximum efficiency, based on the capacity installed on day one.

Advanced modular UPS allow a certain number of modules to be hibernated or switched off if the load decreases or is initially lower than expected, not only does this add extra redundancy but it also allows the other power modules to run at a more efficient loading. To ensure all modules “age” at the same rate, modules can even be cycled to utilise all components for the same period of time. If the loading is not as expected or decreases, the user can physically remove modules as required.

Growth

Power modules are usually mounted into a UPS frame, which may contain a manual bypass switch, main controllers and static switch depending on the manufacturer. While the frame size along with the supply switchgear and cabling determines the total growth in power, a user can start with a lower number of power modules and add further modules, as and when load requirements increase. Thought should be given to the correct mains supply protection for day one capacity and future additional battery requirements, but if these are considered, modular UPS can be deployed as they are marketed on a “pay as you grow” or “scale up as required” basis. Users should ensure that the same modules will still be available from the manufacturer when required.

Conclusion

Modular UPS systems are now dominating the mainstream marketing of the large UPS manufacturers and analysts predict the future market growth rate of modular UPS to overtake traditional standalone systems. To determine which technology will be the most resilient, efficient and cost effective for use, the user and sites requirements should be carefully considered. If the resilience and efficiency required are within acceptable limits from both technologies, it may be a choice of upfront purchasing costs (CAPEX) where standalone may be better vs the operating costs (OPEX) over the lifetime of the UPS. The future servicing and electricity costs along with manufacturer support and availability should also be considered.

There are advantages and drawbacks for both technologies and each site requirement will differ, so discussing your particular power protection requirements with an experienced, helpful and honest UPS specialist such as UPS Power Services will assist in determining which is the correct choice for you.