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Ten tips for choosing a UPS

Business today is energy reliant. Without power, there is no business. Whether it is priceless computer systems and communication devices helping to run your business or simply the lights – it all requires power. Today, uninterruptible power supply (UPS) systems are available for all needs and circumstances, ranging from standalone systems for SOHO (small office home office) applications to solutions for protecting mission critical systems for networking, financial, medical, industrial, telecomms, military and aerospace applications – anywhere continuous power is essential.

A UPS not only provides backup power in the event of a complete power failure but also cleans and conditions the input electricity, outputting what is called `pure sine wave'. There are nine common power problems found in the average workplace environment - power failure, sag, surge, brownout, line noise, spike, frequency variation, switching transient and harmonic distortion - all of which can cause equipment to fail and data to be lost.

A recent report of Venture Development Corporation (VDC), 'The 2002 Power Protection Market Intelligence Program', brings the point home: "The ever growing emphasis on network speed and the sheer volume of transactions that can take place in a fraction of a second make the prospect of downtime that much more ominous each time they accelerate. While 99,9% availability would seem sufficient for the reliability of most systems, in reality it represents the equivalent of 37 000 potential missed emergency calls, or 525 000 lost e-trade transactions ..."

Once you have decided to eliminate power problems by installing a UPS, consider the following points:

1. Types of power protection

There are three types of UPS technology: offline, line-interactive and online.

* Offline - sometimes called standby, it is designed to offer a low price solution to environments that require minimal power protection. An offline UPS offers backup in the event of a total power cut, but does not incorporate any significant power conditioning facility.

* Line-interactive - this UPS technology provides basic power protection at mid-range prices. Line-interactive systems offer protection in the event of an outage but also conditions power, smoothing out peaks and troughs in the power supply. A line-interactive UPS is best used where power conditioning is not crucial to effective operation of the equipment.

* Online - online UPS technology is ideally suited to mission-critical applications. This type of UPS protects against all types of power problems and continuously works to create 100% new, clean, regulated AC power.

2. Planning your power protection

When planning for your power protection requirements, all equipment needs to be considered. This includes not only PCs, but also peripheral equipment and network components. All equipment such as routers or hubs and external data memory should be taken into account. Ideally, UPS should be considered when an IT installation is being planned or a building is first being constructed.

3. UPS capacity to suit your needs

All electrical equipment has a type plate that displays voltage and amp values. These two values multiplied result in the apparent power of the equipment in VA. Most UPSs are rated with VA (kVA) and in watt (kWatt) values. Your UPS should be a 10-20% higher rating than the equipment you need to protect. For example, if your equipment is 750 VA, go for a 1000 VA (1 kVA) UPS unit. Power protection specialists can advise on what equipment is needed to protect the load and any special considerations which should be taken into account.

4. Life span of the UPS

As IT environments grow approximately 5% per annum, it is best to plan in 5-year periods when investing in a UPS. You would therefore choose a UPS with a capacity of 25% above the present capacity requirements to ensure that your investment in power protection will not prematurely outgrow the environment it is protecting. This time span corresponds to the average service life of standard sealed batteries. Battery replacement can extend the life of the UPS in excess of five years.

5. Parallel systems

A parallel system comprises of multiple UPS modules which are installed to operate in parallel to support a common critical load. There are two main reasons for selecting this type of system. The first would be to increase the UPS capacity, which enables the system to power a larger load than possible with a single module. The second reason is to increase the system reliability by introducing modular redundancy.

6. Runtime in the event of a power outage

The typical runtime of UPS systems available on the market is from 5 minutes to up to half an hour at full load. This will depend on the size of the UPS and the equipment it is protecting. The installation of additional batteries extends the runtime accordingly, which is essential for the shutdown of very complex systems.

7. UPS software

Reliable management and monitoring software is essential for the protection of network servers. You should confirm before purchase that the UPS software and your operating system are compatible. Shutdown software with cross-platform capability, which enables you to have network-wide control even if you are using multiple operating systems is crucial. Some UPS manufacturers require you to learn multiple power management software programs. Cross platform software operates the same regardless of the operating system, meaning you only have to learn one package.

8. Remote monitoring

A sophisticated power management software enables the remote monitoring of the UPS from anywhere on the network. This is done by a serial communication port, SNMP (simple network management protocol) software, or via the Internet, and enables the IT manager to control and monitor UPSs on the network, wherever they are in the world.

9. Maintenance

Preventative maintenance and service of your UPS is essential. Even the most superior UPSs, like all other machinery, need to be maintained. Many UPS companies will offer service agreements, ranging from basic maintenance to full service contracts including 24/7 call-out, parts, labour and battery replacement. Investigate the company's service organisation to make sure they have the expertise and the resources to fulfil the service contract they offer you. Consider such things as how far their nearest engineer is to you, which will affect their call-out times, or do they have an extensive stock of spares - which will affect the speed at which they can replace any parts that have gone wrong.

10. Maintenance bypass

The manual bypass switch is mainly used for service purposes. This switch is of a 'make before break' type that guarantees a transfer from the static switch directly to the power line and back again without any kind of interruption. This ensures mission-critical equipment is powered, even when essential maintenance work is carried out.

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