A Surge Protector Should Last A Long Time

A surge protector must withstand the largest surge expected to be encountered, and must survive the expected number of pulses. Based on the applications, the surge protector should be designed and tested to meet minimum of 10, or 20 kA 8/20 us and 5 or 10 kA 10/350 us as detailed in ANSI/IEEE C62.41.2, Recommended Practice on Characterization of Surge Voltages in Low-Voltage (1000 V and less) AC Power Circuits, and IEC 61643-1, Surge Protection Devices, Connected to Low-Voltage Power Distribution Systems. Fuses should not operate during the surge, and the let through voltage must be less than equipment susceptibility.

A properly designed and specified surge protector should not fail in service. A surge protector that fails due to surges or lightning (termed "self-sacrifice" by some manufactures) most likely has been inadequately designed.

It is a common misconception that MOVs have a limited service life due to MOV degradation. MOVs have been used for more than 20 years. It is true that MOVs must be derated according to life, and the size and number must be chosen to provide sufficiently derated pulse life. A correctly sized DEHN surge protector easily exceeds the pulse life required for a service life of more than 20 years.

To provide sufficient overvoltage immunity, the arrester should withstand a sustained +25% line voltage swell. Some manufacturers use MOVs or SADs which clamp lower than 25% above the sine wave in order to claim lower let through voltages at the terminals of the surge protector in published literature. This may result in surge protector failure during substained voltage swells. DEHN surge protectors have the ability to withstand overvoltage swells of +25%.

Installed let through voltages is more dependent on connection lead length (200 volt per foot for a 10 kA 8/20 us or 10/350 us surge) than on a small difference in clamping voltage at the terminals of the protector. DEHN surge protectors feature an integrated fused disconnect that eliminates the lead length and bends associated with the use of a seperate disconnect.

A business without a TVSS unit runs the risk of lost data, erroneous signals and false system operations. With Dehn's quality TVSS products you can always rest assured that business is in good hands. Contact us today to learn more about our lightning and surge protection products.

• A Surge Protector Should Be Effective
• A Surge Protector Should Last a Long Time
• A Surge Protector Should Be Safe
• A Surge Protector Should Be Easy To Use