FAQs - Modular UPS

A modular UPS uses individual power modules that hot-swap into a single UPS frame that contains static and manual maintenance bypasses and electrical connection infrastructure, rather than being a single fixed-capacity unit which is referred to as a monobloc UPS. Modular UPS offer ‘pay-as-you-grow’ functionality because from day 1 you can size the system to your current load and add modules to meet growth and/or resilience (N+X) requirements. With a modular UPS you do not have to oversize the UPS to meet the total expected lifetime load. You do, however, have to ensure your UPS frame is sufficient sized to house the number of UPS modules you may need in the future.

Yes, and this is a key feature of a modular UPS system. The UPS modules are hot-swappable modules. Modules can be removed for service and maintenance and extra modules added without the need to power down the UPS system. The UPS continues to protect the load during module removal or insertion into the UPS frame. When a module is inserted, the system goes through a number of self-tests before the module is accepted electrically into the frame and brought online.

For a modular UPS, the recommended minimum maintenance requirement is one preventative maintenance visit per annum. To this can be added additional battery testing at the battery block level. Whilst a modular UPS will self-test every 24hours, the preventative maintenance visit provides visual inspect, alarm and operational log review, cleaning and inspection of other critical components including capacitors and fans. The batteries are the principle concern as a battery ages, with standard VRLA (valve regulated lead acid) batteries requiring replacement in years 3-4 or 7-8 depending on their design life. Lithium batteries have a longer working life of 10-15 years. Regular UPS servicing as part of a UPS maintenance contract is the best way to ensure your UPS remains operational and in the best health to protect your critical loads.

When the term N+1 or N+2 or N+3 is used in relation to UPS design, this refers to adding extra capacity to a system, so that if a module fails (or is removed from service) the remaining modules continue to power the load. N is the running capacity of the system and the number represents how many additional modules are available for resilience and redundancy in the UPS system design. If a module fals, the others take over automatically with no break in the critical power path to the connected load.

Monoblock are fixed capacity uninterruptible power systems. To scale or add N+X resilience, another monoblock UPS must be installed i.e. 2 × 100kVA to give 100kV N+1 or 200kVA capacity. With a modular UPS, an additional UPS module can be added to a UPS frame to provide N+1 redundancy or increase the power capacity up to the maximum number of UPS modules that can be housed by the frame. The modular UPS system can be expanded further by adding another UPS frame.

Modular uninterruptible power supplies include a static bypass switch either built-into each UPS module, referred to as a decentralised approach or into the UPS frame and referred to as a centralised bypass arrangement. The UPS frame may also include a centralised maintenance bypass or an external maintenance bypass switch may be installed with the UPS system.

Some smaller modular uninterruptible power supplies include space within their UPS frames for plug-in batteries. The alternative is to install the batteries in a separate battery cabinet or on a battery stand.

The installation of a modular UPS starts with a site survey to asses the load to be protected, electrical supply available and required, space, floor loading and cooling load requirements. With this information our Projects Team can generated a plan for the installation, including an external maintenance bypass, electrical installation, commissioning services and load bank testing (if required) with minimal disruption to the site and IT services.