Surge protection device for complex transients

In a power distribution system having a return line and having an upstream breaker/fuse connected to a power line, an apparatus for protection from voltage transients, the apparatus comprising:

• a low-pass filter operatively coupled across the power line and the return line of the power distribution system, wherein the low-pass filter has a corner frequency sufficient to slow a rise time of high-frequency components of the voltage transients for the transient voltage suppressor to have time to suppress the high-frequency components to the clamping voltage;
• a transient voltage suppressor operatively coupled across the power line and the return line of the power distribution system to suppress voltage transients to a clamping voltage;
• and
• a crowbar operatively coupled to both the return line and through the power line to the breaker/fuse of the power distribution system in a configuration to short the power line to the return line to open the breaker/fuse when the transient voltage suppressor fails to suppress the voltage transients to the clamping voltage.

In a power distribution system having an upstream breaker/fuse connected to a power line, an apparatus for protection from voltage transients, the apparatus comprising:

• a low-pass filter operatively coupled across the power line and the return line of the power distribution system;
• a transient voltage suppressor operatively coupled across the power line and the return line of the power distribution system to suppress voltage transients to a clamping voltage, wherein the transient voltage suppressor comprises a failure detection component to produce a failure status signal indicative of a failure condition;
• and
• a crowbar operatively coupled to both the return line and through the power line to the breaker/fuse of the power distribution system in a configuration to short the power line to the return line to open the breaker/fuse when the transient voltage suppressor fails to suppress the voltage transients to the clamping voltage, wherein the crowbar comprises a thyristor or a triac and wherein the thyristor or triac comprises a gate pulsed by current resulting from the failure status signal from the transient voltage suppressor.

In a power distribution system having an upstream a main breaker/fuse connected to a power line, an apparatus for protection from voltage transients, the apparatus comprising:

• a low-pass filter operatively coupled across the power line and the return line of the power distribution system;
• a transient voltage suppressor operatively coupled across the power line and the return line of the power distribution system to suppress voltage transients to a clamping voltage;
• and
• a crowbar operatively coupled to both the return line and through the power line to the breaker/fuse of the power distribution system in a configuration to short the power line to the return line to open the breaker/fuse when the transient voltage suppressor fails to suppress the voltage transients to the clamping voltage, wherein the crowbar is sensitive to both low-frequency and high-frequency components in the voltage transients;
• and
• wherein the low-pass filter has a corner frequency below a frequency of the high-frequency components to prevent shorting by the crowbar upon the high-frequency components so that the crowbar trips only when the transient voltage suppressor fails to suppress the voltage transients to the clamping voltage.