What Are the Main Components of a UPS System?

Understanding your UPS system and how it works can help you troubleshoot any issues if they arise and ensure your business is protected when there is a disruption to your power supply.

There are four main components in an online double conversion UPS system – Rectifier, Inverter, UPS Batteries and Static Bypass Switch.


The rectifier charges the batteries and converts utility AC power to DC power. Together with the inverter, the rectifier allows for protection from power anomalies and delivers clean power to the load.


The inverter converts DC power from batteries (or from the rectifier) back into AC power for load use. In double conversion UPS systems, the rectifier and inverter are used together to convert AC to DC and DC to AC to protect systems from any power anomalies.


Batteries are the core of the UPS System and are the main source of UPS failure as they are the most likely component to fail. Batteries fail for a range of reasons – physical damage, sulphation, over cycling, poor maintenance and more. Testing your UPS batteries regularly plays a key role in ensuring their reliability.

Static Bypass

If there is a fault in the UPS system, the static bypass automatically connects the load to the mains supply and allows the incoming power to divert around the rectifier, batteries, and inverter.

The static bypass lets critical systems continue functioning even if the UPS’s internal components fail.

Preventative maintenance is vital in ensuring your UPS system’s efficacy when there is a disruption to the mains power supply.

Preventative maintenance includes:

  • Check of all electrical connections
  • Check of circuit breakers, fuses, cabling, and transformers
  • Battery inspection for signs of damage
  • Check of functionality
  • Check of performance history logs

At Shanahan Power, you can opt-in for our Asset Care Management, which covers preventative maintenance, general maintenance and provides access to our 24/7/365 Breakdown Assist Facility.

Our team is on-hand to offer advice on preparing your business for power outages. Contact us to find out more!