Regular Maintenance will avoid the fall-out from An Exploding Capacitor
How do you get round the problem of an exploding capacitor?
The short answer is to make sure it doesn’t fail in the first place. By and large, that will be determined by having a reliable UPS system, together with an appropriate maintenance arrangement in place, to make sure everything is functioning as it should be.
With capacitors, however, their function is invisible. Hidden behind casing, they go about their business out of sight and pretty much out of mind.
The only problem is that they aren’t simply components that can be left to their own devices for an indefinite period – as this video graphically demonstrates.
This is a capacitor providing an impromptu firework display, albeit under controlled conditions, highlighting what can happen when an ageing piece of equipment short-circuits. No one was hurt during its making – but it just goes to show what might have occurred if this capacitor had been operational in an area responsible for running a company’s IT equipment. An explosion, however rare, could cause potentially untold damage – risking public safety, disruption to business and a high cost of repair.
A capacitor left unchecked can be a law unto itself and an accident just waiting to happen.
Their average life capacity is usually somewhere between five to eight years. On newer versions, where they are imbedded in a state-of-the-art modular UPS system, this could be longer – but, eventually, they will need replacing.
That doesn’t mean that after eight years, a capacitor will automatically give up the ghost and become a computer room missile.
But we would strongly recommend that anyone with a responsibility for UPS procurement and servicing doesn’t leave it to chance.
What is a capacitor?
A capacitor is a passive two-terminal electrical component which stores and enhances electrical energy in an electric field, known as capacitance. It isn’t designed to dissipate energy.
Each one basically sits inside a small can, often grouped together in banks – depending on the size and scale of the UPS installation. They comprise of two long strips of aluminium, which can be tens of metres long and rolled into a bobbin, separated by a dielectric material, typically a polymer strip. The dielectric, which is non-conducting, is there to increase the capacitor’s charge capacity. The same principle applies to either DC or AC capacitors.
Over time, as a result of various factors, the plastic deteriorates, the insulation becomes compromised, current starts to flow between the two strips which can lead to arching.
Why do they fail?
There are various reasons why a capacitor may fail. Overheating, voltage surges, current stresses, defective equipment and good old fashioned wear and tear can all contribute to a malfunction.
The point is that the vast majority of power capacitor failures, whether they occur in large or small uninterruptible power supply (UPS) systems, can and should be prevented at source.
When they do occur, the likelihood is that the whole UPS system will shut down, resulting in a potentially hefty repair bill.
The good news is that with the combination of advanced UPS systems and regular maintenance, capacitors should only do what they are meant to do – store energy efficiently and maintain an extremely low profile.
For both new, upgraded or replacement UPS systems, at MPower we would recommend the use of easily maintainable, standardised modular components, which will be virtually failsafe, provide optimum performance and long term peace of mind.
The vast majority of our clients are on maintenance contracts, ensuring that our field engineers make regular site visits to inspect all working parts, like capacitors, are behaving as they should, to ensure they haven’t been compromised by any unforeseen power surges or changes in current. This is standard, preventative maintenance which we would strongly advocate for anyone running a UPS system in the workplace.
If, however, you are in any way concerned about your current level of maintenance on your UPS, contact the MPower UPS Maintenance Division on 01420 82031.
Better to be safe than sorry.