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Lightning

Safeguarding UPS systems from the most damaging threats

By Jack Ward, MD of Powermode

With the frequency of power outages and the critical nature of South Africa’s power grid, it is important that standby power plants, particularly in large enterprises, are safeguarded from threats that could disable them when they are needed most.

If an uninterruptible power supply (UPS) system malfunctions it is almost certainly to be at an inopportune moment – when a power outage occurs. In such instances the computer system the UPS supports will shut down and valuable data could be corrupted or lost. Questions will soon be asked as to how soon repairs could be effected. Almost impossible to calculate will be the cost to the company in terms of downtime.

UPS systems are constantly on standby, powering silently in the background. Imperceptibly, they face a number of threats to their wellbeing on a daily basis.

Probably the number one cause of a UPS malfunction is the failure of its batteries. Battery life is influenced by many factors including storage conditions, ambient temperature, battery chemistry issues and shelf-life. As a rule of thumb, a UPS battery has a general life cycle of three to six years.

Battery maintenance should be top of a UPS user’s priority list. A good maintenance regimen will help prolong battery life while keeping a note of where the battery is in its life cycle will provide an indication as to when failure is imminent.

Transient spikes, due to South Africa’s unstable electricity grid, are another threat. Serious damage is likely to be caused to the input side of a UPS – the filter/rectifier siting – when a transient spike occurs. Once again, preventative maintenance will help identify the damage and rectify it before catastrophic failure occurs.

The scourge of Highveld weather, lightning, can do serious damage to a UPS system and to the highly sensitive computer systems it is tasked to protect. A common misconception is that a UPS system constantly protects itself and the equipment load from lightning strikes. If the amount of energy in the transient (the lightning strike) is large enough, damage will occur. Appropriate repairs can then be initiated.

As small as a two-rand coin or as large as a cool-drink can, capacitors, like batteries, degrade over time. The effects of time many not be apparent, but a single failure will have a domino effect, leaving the other capacitors to work harder and fail sooner. Most UPS systems contain as many as a dozen or more of these simple devices that store and release electrical energy. Tests will identify failed capacitors which are easily replaced.

Dust is the enemy, steadily advancing to block filters and cause progressive overheating of UPS systems. Regular monthly inspections are required to address this problem. Fortunately, filters are the least most expensive components of an effective UPS maintenance plan.

Contactor failure is another threat to UPS systems. Contactors, which are also prime collectors of fine dust and other resistive particles, require regular inspection and cleaning to ensure optimum performance and to guard against premature failures.

The failure-proofing of relays is not usually at the top of the maintenance schedule, however, technically-aware UPS owners understand that the sticking of welded relays may go unnoticed for long periods of time. The problem is revealed only when emergency change-of-state events occur. Appropriate inspection procedures are able to detect problems before they arise.

Surge suppression devices, including metal oxide varistor (MOV) devices are often compromised by lightning strikes. Regular maintenance regimens will most certainly be able to determine whether these devices are fully functional.

Selecting a UPS system that matches an organisation’s exact needs is vital to UPS longevity. Consulting a knowledgeable provider with experience in the UPS industry before making an investment is prudent as is selecting a system that can organically grow in tandem with the company’s expansion plans.