Uninterruptible power supplies are no different to other critical systems (cooling and fire suppression) within a server room or data centre environment. For a UPS system to provide no-break backup power on demand, it must be regularly inspected and maintained. Most UPS failures are down to poor battery health, leading to shorter than expected runtime and IT load downtime. There are other factors that can also limit the ability of a UPS to keep critical loads running and like battery health, they can only be identified and/or prevented from regular inspection and maintenance.
At least one UPS preventive or preventative maintenance visit (PMV) per annum is recommended by UPS manufacturers both inside and outside warranty. For some older systems and those in high security, military, and larger data centres sites, two visits may be required to meet maintenance schedules and service level agreements.
A UPS preventative maintenance visit can be performed as a one-off inspection (typically known as a health check). This is typically the case for third party systems being inspected for inclusion within a service or UPS maintenance contract.
More generally, preventative maintenance visits are included within a UPS annual maintenance contract to ensure the continuing health and availability of the UPS, including replacement of consumable items such as batteries, fans, filters, and capacitors as required.
Most companies will offer a range of UPS maintenance contracts. These will differ in their level of comprehensiveness, response times offered (working or clock hours from 8 working hours to next day to 4 clock hours) and emergency cover periods (Mon-Fri working hours excluding bank holidays or Mon-Sun 24/7 clock hours).
|UPS Maintenance Contract||Platinum Level||Gold Level||Silver Level||Bronze Level|
|Preventative Maintenance||1 per annum||1 per annum||1 per annum||–|
|Emergency Response||4 clock hours||8 working hours||12 working hours||best endeavours|
|24/7 technical hotline||included||included||included||working hours|
|Battery Cover||extra cost||extra cost||extra cost||–|
|On-site Crash Kits||option||option||option||option|
|247 Remote Monitoring||option||option||option||included|
|Monthly Status Report||option||option||option||alerts reported|
|Individual Battery Testing||option||option||option||–|
|Load Bank Testing||option||option||option||–|
Whilst a typical UPS maintenance contract will cover 1 year (12 months), 3- and 5-year contracts may be available with a discounted price.
It is worth noting that one of the prerequisites for a maintenance contract is the site having an external UPS maintenance bypass switch as part of the UPS installation.
A site visit will be scheduled and may take place during or outside normal working hours. The more critical the site, the more often the UPS is inspected and maintained outside working hours, when workloads are less to mitigate the risk of power interruption and downtime, especially where the UPS is installed as a single rather than a parallel/redundant system.
Whilst UPS engineers will generally follow a planned preventative maintenance schedule, additional items may be included to meet client requests.
Typical areas and topics covered during a preventative maintenance visit include:
Regular service visits and inspections will help ensure that the uninterruptible power supply reaches its targeted working life. A typical single or three phase online static UPS should be capable of at least 10 years of services when maintained in accordance with the UPS manufacturer’s recommendations, attended by certified UPS engineers trained by the manufacturer and where manufacturer supplied, or recommended consumables and parts are used.
Every UPS system has consumable parts that must be replaced before their failure. A typical UPS maintenance schedule over the working life of a UPS system is outlined in the table below.
|Visual inspection of electrical connections||1 Year|
|Check of alarms on front panel display||1 Year|
|Check of DC filter capacitors||1 Year|
|Fan control & cleaning||1 Year (*)|
|Check of alarm History||6 Months|
|Cleaning of magnetic parts||1 Year (*)|
|Cleaning of electronic boards||1 Year (*)|
|Check of input voltage||1 Year|
|Check of output voltage||1 Year|
|Check of bypass functionality||1 Year|
|DC capacitor replacement||8 Year|
|AC capacitor replacement||8 Year|
|Cooling Fans replacement||4 Year|
Note (*) where UPS operate in particularly dusty environments, the frequency of inspection may be increased.
For more information on Preventive Maintenance Strategies for Data Centres, read this article by Schneider Electric:
If a UPS system is to be available 24/7 and provide instantaneous backup power when the mains power supply fails, it must be maintained as part of a UPS maintenance contract. A contract that simply provides emergency response will not provide the level of cover provided. Any UPS maintenance contract must include at least one comprehensive annual preventative maintenance visit.
Consumable parts must be replaced when identified and corrective actions taken in response to any issues identified by the UPS service engineer. Only then can a site be certain that its uninterruptible power supply will be in the best possible health and ready to protect critical loads from unplanned momentary power outages, short power interruptions and more long-term mains power supply failures.
Server rooms should be designed to provide a secure and managed environment in which to run critical IT servers and network infrastructures. Facilities vary in size from IT closets to computer rooms, Edge to regional and even hybrid datacentres. Whatever the size of the setup, each will have a core set of systems that require regular inspection and maintenance in order to ensure their uptime and resilience.