1. Right-sizing the UPS and backup battery power supply

2. UPS battery replacements and refurbishments

lead-acid 5-year or 10-year design life, requiring replacement around years 3-4 or 7-8 respectively and when used within a 20˚C ambient environment. Cooling fans are another example of a UPS consumable which should also be inspected annually and replaced according to fan manufacturer recommendations.

3. UPS ECO Mode

a line-interactive UPS, so the load is powered by the bypass line with the inverter inactive but ready to take over if there’s mains supply failure or fluctuation. This short break in continuous power is the main drawback to using ECO mode, particularly with sensitive equipment.

4. UPS maintenance and routine inspections

Regular maintenance of UPS systems is critical to the availability and resilience of an uninterruptible power supply and should be budgeted for when first installed. Without regularly maintaining UPS systems, sudden failures can occur with over 80% caused by a poorly maintained battery set. However sophisticated a UPS may be, the fact is that uninterruptible power supplies have consumable parts that require regular inspection to ensure optimum performance including overall UPS energy efficiency.

5. UPS Remote Monitoring

Uninterruptible power supplies should be monitored over an Ethernet/IP network for alarm conditions. Continuously monitoring the UPS system can establish load patterns over time and provide enough time to respond to issues that could affect UPS energy efficiency and operational resilience. Two specific alarms that can indicate energy efficiency include:

Overload and bypass alarms: if the load connected to the UPS power supply is greater than its rated output, an alarm will be issued. If the overload is large enough or there is an internal fault condition, the uninterruptible power supply may go into bypass mode

Over temperature alarms: can indicate an internal fan failure or that ventilation into and out of the UPS cabinet is restricted. Long term higher internal ambient temperatures can lead to component damage as well as requiring fans to run at higher speeds.

If the battery set is within a separate cabinet or room, the installation of a separate battery temperature sensor is recommended.

UPS energy efficiency summary

Over the last two decades there has been a significant improvement in the datacentre UPS energy efficiency levels. The use of IGBT-based rectifiers and inverters has helped to dramatically lower fixed energy efficiency losses and flatted the efficiency curve out over a wide load range, from as low as 25% to 100% loaded. There have also be improvements in transformer design and the widespread introduction of modular datacentre UPS by many of the leading UPSmanufacturers. Energy efficiency levels have risen from around 70-80% to around 96% for most online systems and 97-98% could eventually become the norm. However, there will always be the need to correctly size both the UPS and its battery set, monitor installations and ensure that they are correctly maintained if the design calculations are to be proven in use.