BACKGROUND OF THE INVENTIONS

1. Technical Field

The present inventions relate to surge protection devices and, more particularly, relate to surge protection devices designed to protect electronics from conducted transients.

2. Description of the Related Art

Conventional surge protection devices (SPDs) almost universally use metal-oxide varistors (MOVs) placed between the power and return lines. The MOVs begin conducting at high voltages, thereby shunting away unwanted energy and acting to limit the voltage that the subsequent load experiences. However, MOVs and other transient voltage suppressors, including transient voltage suppression diodes (TVS diodes), gas discharge tubes (GDTs), and avalanche diodes, have a finite turn-on time that is typically in the tens of nanoseconds or greater. This limits their effectiveness against very fast transients. Also, transient voltage suppressors have a maximum amount of energy that they can dissipate before overheating and suffering catastrophic failure. For long-duration transients, i.e., those that last milliseconds or longer, conventional MOV-based surge protection devices overheat and fail. The same is true for designs based on other transient voltage suppressors, including transient voltage suppression diodes, gas discharge tubes, or avalanche diodes.

Based on knowledge, no surge protection devices incorporate the combination presented in this invention disclosure. The closest technology found was that of a ground-fault circuit interrupter (GFCI), which detects an imbalance of current flowing in versus out and opens a breaker under such a condition. It is distinctly different than this invention in a number of ways. First, a GFCI detects a current imbalance, whereas this invention detects an overvoltage condition. Second, it does not use a transient voltage suppressor, or any of the circuitry disclosed in this invention to limit the imbalance or trigger the protective breaker. Third, a GFCI is a safety device designed to protect users from electrocution. The invention described is a surge protection device designed to protect electronics from damage, not users from harm. Finally, the GFCI opens a protective breaker as a result of an unwanted fault current, whereas the invention intentionally creates an overcurrent condition to trip an upstream protective device.

