Critical Issues - Roles and Reliability

A transient voltage surge suppressor system guards against voltage transients, commonly known as surges. These can cause electronic equipment to fail. It simply stops working because its microprocessor has been damaged. Not all transients break the system immediately. Some produce a phenomenon known as electronic rust, which slowly wears down the microprocessor until it fails.

Transients are caused by a variety of things that surround us in everyday life. The most common is lightning. Lightning striking on or near power lines can cause surges in excess of 50,000 volts. Even with a TVSS system, a strike like this is likely to damage your equipment. Nothing will protect you from a direct lightning strike.

Other things in your home or business cause transients, too. Every time a large piece of electrical equipment is turned off, a brief surge, called a switching transient, results. These are much smaller than lightning transients, but occur much more often. Switching transients are also generated when power line switching is done for safety or maintenance to uphold reliability.

There are a number of concerns which must be evaluated before purchasing a TVSS and several that must be considered when installing one.

A TVSS will not eliminate transients. Its job is to reduce the magnitude or energy content of the transient. This reduction specification is called the clamping level. Only the amount of energy above this "envelope" will be affected. Transient energy below the peak envelope level will not be altered.

Again, after some amount of usage, a TVSS will fail. MOV-based devices -- again, the most common technology -- fail in an open position, so this should be indicated by some external method, typically a light.