Transient surges - the hidden problem

Edited by the Engineeringtalk editorial team Dec 10, 2002

Nathan Briggs, Technical Managing Director at Advance Galatrek explores why mains transients are the scourge of modern commerce and industry.

Nathan Briggs, Technical Managing Director at Advance Galatrek explores why mains transients are the scourge of modern commerce and industry.

Totally invisible, but with devastating consequences - transients are the scourge of modern electronics.

Like a drop of water wearing away a stone, they increase component stress until, one day, your systems will fail without warning.

New research tells us that 88.5% of all power disturbances are caused by transient voltages.

And, even though you might think your data and production processes are safe, the truth is that they will have very little - if any - protection against this potentially disastrous phenomenon.

The damage caused by a series of transients can be catastrophic.

Unlike a simple power interruption, where downtime and possible data loss are the worst consequences, transients can cause irreparable damage to sensitive components such as servers, PABX phone systems and other critical devices.

And don't think that it's just the occasional lightning strike that will put your business at risk.

Statistics show that four out of five transients are caused by events other than lightning strikes.

In fact, the vast majority of damaging spikes arise from machinery situated either on or near the site, with up to 20% of voltage spikes caused by sources as mundane as photocopiers and fluorescent lights.

Worse still, conventional power protection solutions just aren't equipped to cope with the massive energy spikes from a typical voltage transient.

And, with peaks as high as 20kV from an average lightning strike, even a single transient can easily destroy sensitive computing and comms equipment.

You can't afford to rely on the surge protection that some power continuity systems feature as standard, especially with modern computing and comms applications.

When power is restored after an outage, large transients are often generated while the supply settles down - enough to cause irreversible harm to critical electronic circuitry.

The internal surge protection in most power protection equipment relies on a single MOV (metal oxide varistor) device.

But just a single voltage spike can easily destroy these devices - leaving critical computing and comms components open to devastation.

Only a properly designed TVSS module can offer completely reliable protection against this kind of damage.

Very few basic power distribution strips - and even fewer internal protectors - actually contain both thermal protection and surge protection in the same component.

This means that often the only way of determining whether a basic surge protector has failed is if the input fuse blows, or, worse still, if the unit catches fire.

Many voltage surge suppression manufacturers make unrealistic claims about their TVSS units, especially when they contain gas discharge tubes.

But hundreds of hours of research have proved that these units cause more problems than they solve.

Because GDTs cannot effectively cap the voltage spike caused by a rising waveform, this reduces the life of the metal oxide varistors also found in these devices.

And, because GDTs are an open circuit device, they provide no indication of their inability to protect the load in the event of failure - often with potentially disastrous consequences.

Latest studies have proven that the best type of transient suppression device is the SAD, or silicon avalanche diode.

These semiconductors can respond very rapidly to a transient voltage, and can be specified with clamping voltages that range from a few volts to several hundred.

A matrix configuration is the perfect component structure for a TVSS device.

The individual components are arranged in separate assemblies - a design that offers all the advantages of SADs and MOVs, as well as providing additional reliability and crucial performance where they are most needed.

TVSS devices using matrix technology have an anticipated survival time of 100,000 strikes.

Better still, even if the full transient were routed through a single component in the matrix, the life expectancy would be several hundred strikes.

So, to take a simple precaution that can save thousands in lost production, downtime, data loss and equipment damage, fit TVSS devices to your critical components, or live to suffer the consequences.