Most people who own a car these days understand that regular servicing is essential - particularly if reliability, reduced running costs and minimal repair are desired.
It is surprising, therefore, that in today's 24/7 business environments - with ultra high-density data centres dependent on reliable uninterruptible power supplies - is so often overlooked. Of course, most people use their car everyday, so it becomes apparent when a fault occurs but what about the back-up vehicle sitting in the garage waiting for just such a moment? Will it start?
Like all electrical systems, UPS require regular maintenance. Here's a guide to keeping your system ready for action:
The value of UPS maintenance contracts
Some businesses shy away from UPS maintenance contracts because they think them unnecessary, costly and invasive to the business. Nowadays, however, modern UPS systems, attached to mission critical equipment, have an internal or external maintenance bypass, which allows servicing to be carried out without having to shut down the whole network and lose vital productivity. Proper maintenance, carried out in a timely and effective manner, can prolong the life of the UPS, increase its effectiveness and achieve a better return on investment.
Maintenance and key UPS components
As the UPS's job is to supply a continuous source of clean energy, one of its main components is a rectifier, fed by mains electricity, which converts incoming mains power from AC to DC. This charges the UPS's battery and feeds an inverter. In an on-line UPS, the inverter continuously powers the load with regenerated, clean sine-wave electricity, making it vital that the UPS be tested regularly to ensure that both rectifier and inverter are working correctly.
A UPS also contains consumable parts that will age or even fail over time. The following elements should be regularly checked and tested:
&bull Batteries
&bull Cooling system software
&bull Cables
&bull Generators
&bull Fans
&bull Local air-conditioners.
Software
The software side of a UPS system is the least problematic in terms of maintenance - but one of the most crucial elements when it comes to monitoring and measuring the effectiveness of the system itself. UPS software, used for on-site or remote monitoring and fault reporting, can itself be maintained through regular updates and basic IT housekeeping.
Cables
UPS problems can often be traced to faulty, mis-patched or damaged cables so these need to be checked regularly as well as when a fault occurs. The cables that attach the UPS to the load and the network should be checked for wear-and-tear - as should connectors. Faults can result from poor connections. If a fault does occur and the cause is not immediately apparent, all UPS cables should be checked and tested thoroughly.
RS-232 ports can be the weak point of a UPS computer system. These can be minimised by following a few simple steps during installation:
&bull Where possible, avoid wiring runs longer than a few metres.
&bull Install high-performance surge suppressors on modem connections.
&bull Always use properly constructed, high-quality, shielded RS-232 cables.
Maintaining a source of standby power
Generators, which are usually fuelled by diesel, provide an emergency source of standby power when mains power, for whatever reason, is no longer present. Not only do they need to be checked and tested, regularly, by specialist engineers but they also need to be tested under load conditions. Special measures need to be exorcised to preserve business continuity during testing:
&bull Check for environmental breaches (exhaust and heat emissions, vibration and noise levels).
&bull Run back-up generators weekly to ensure safe and efficient working of their mechanical parts and to allow for monitoring and maintenance.
&bull Look for tell-tale indicators such as raised emission levels or significant increases in fuel consumption.
&bull Remember to check heat ducts and exhaust pipes.
Batteries
Because UPS batteries employ a chemical process, which is corrosive, they are consumable, usually maintaining a design life of between five and 10 years. What's more, few UPS users take sufficient precautions to ensure batteries are holding their charge and will work when required. It is not difficult to maintain them as most modern UPS systems have built-in automatic battery testing which can be scheduled to occur every 24 hours. Normally instigated from a front panel push-button or keypad, or initiated remotely via a network connection, it is far easier now to keep an eye on these essential UPS components.
The efficiency of sealed lead-acid UPS batteries is dependent on age, state and environment. They should be checked regularly for corrosion, discharge and wear-and-tear. If any of these are apparent, the battery should be replaced immediately.
The most important aspect for preserving the life of UPS batteries is maintaining a constant temperature. Housing should be kept at a consistant 25 ?C (every five-degree increase or decrease in this temperature halves battery life). It is important, therefore, to maintain it wherever the UPS is housed. This demands an effective cooling system, which in itself must be properly maintained.
The largest UPS installations, typically above 500kVA, often use flooded cell batteries requiring periodic inspection of electrolyte chemical and plates. Maintenance includes measuring and recording of electrolyte specific gravity and replenishment of water. Smaller UPS batteries, which are valve regulated, are supplied in sealed systems and do not require special maintenance, other than inspection for corrosion, and testing.
Keep it simple and well documented
The criticality of certain applications will dictate the degree of protection they require. It is essential that businesses have a sound, documented overview of all applications and equipment on the network. A network survey should be carried out to establish this.
Conclusion
Maintenance should be routine and need not consume large numbers of man-hours. It is crucial to successful UPS implementation and need not be complex or disruptive to business (particularly as modern UPS maintenance bypasses ensure continuity for the duration of routine servicing).
If these simple rules are followed and maintenance becomes routine, the life of the UPS will be prolonged and business better protected against inevitable power fluctuations, failures and electrical disturbances.
