| Re: Surge Suppressors
There seems to be a lot of mixed signals on this topic.
According to Kenneth Brown, chairman of the Technical Committee at NEMA 5-VS Low Voltage Surge Protective Devices: “If MOVs are used within their well-defined specifications, degradation due to the environment is not likely. However, the environment that MOVs are used in is not well-defined. Low voltage ac mains are subject to lightning strikes, switching transients, voltage swells/sags, and temporary overvoltages (TOVs), and other similar disturbances. Due to the variety of disturbances that MOVs are exposed to, degradation or failure are possible in many applications.”
Also, according to Sensors Magazine: “Not all lightning is created equal. About 30% of all lightning strikes have a peak current of over 10 kA, while about 10% of all lightning strikes have a destructive current of over 50 kA (yes, that exceeds the rating of the protector you just bought!) A percent or two of strikes get over 100 kA! Strikes have even been recorded with current peaks well over 200 kA!”
However the above quote needs to be taken with a grain of salt. Due to a variety of factors, the current actually induced into a power line from lightning can be considerably less than these figures.
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