Solid state surge suppressor

Claim 2

In an electric system for supplying D-C power from a voltage source to an electric load, a solid-state voltage surge suppressor connected across said source for limiting the magnitude of voltage surges to a predetermined maximum and for dissipating their energy, said suppressor comprising: a. non-linear resistance means having a negative currentresistance characteristic; b. normally non-conductive controllable electric switch means connected in series circuit relation-ship with said non-linear resistance means; c. triggering means operative in response to a voltage surge across said series circuit for rendering said electric switch conductive when the potential of said surge attains a preselected level which is is a function of the rate of rise of said surge, said triggering means comprising: i. frequency dependent attenuating means, having an input and an output, for attenuating a voltage provided at its input which represents the voltage across said series circuit to provide an output voltage of reduced magnitude at said output, the degree of attenuation of said input voltage decreasing as the rate of rise of the input voltage increases, said attenuating means comprIsing a resistor-composed-voltage divider connected in parallel with a capacitor-composedvoltage divider, the values of the resistors and capacitors in said attenuating means being such that the degree of attenuation for a fast rising input voltage is slightly less than the degree of attenuation for a slow rising input voltage; and ii. level sensitive means coupled to the output of said variable attenuating means for rendering said switch means conductive when the output voltage reaches a preestablished level; and d. turn-off means for automatically causing said electric switch means to cease conducting.

Claim 3

The suppressor as specified in claim 1 wherein the degree of attenuation for a fast rising input voltage is approximately 80 percent of the degree of attenuation for a slow rising input voltage.

Claim 4

The suppressor as specified in claim 2 wherein said electric switch means comprises a thyristor.

Claim 5

In an electric system for supplying D-C power from a voltage source to an electrical load, a solid state surge suppressor connected across said source for arresting surges in the system while limiting such surges to a predetermined maximum, said suppressor comprising: a. non-linear resistance means having a negative current-resistance characteristic; b. a normally non-conductive thyristor connected in series circuit relationship with said non-linear resistance means, said thyristor being rendered conductive in automatic response to a voltage surge across the series circuit; c. means for automatically causing said thy-ristor means to cease conducting comprising: i. an oscillatory circuit including a capacitor and an inductor connected in shunt with said thyristor via a normally non-conductive electric switch; and ii. triggering means for rendering said electric switch conductive when the magnitude of the voltage surge drops below a first preselected level if the voltage appearing on the capacitor of the oscillatory circuit is above a second preselected level.

Claim 6

In an electric system for supplying D-C power from a voltage source to an electrical load, a solid state surge suppressor connected across said source for arresting surges in the system while limiting such surges to a predetermined maximum, said suppressor comprising: a. non-linear resistance means having a negative current-resistance characteristic; b. a normally non-conductive thyristor connected in series circuit relationship with said non-linear resistance means, said thyristor being rendered conductive in automatic response to a voltage surge across the series circuit; c. means for automatically causing said thy-ristor means to cease conducting comprising: i. an oscillatory circuit including a capacitor and an inductor connected in shunt with said thyristor via a normally non-conductive electric switch; and ii. triggering means for rendering said electric switch conductive when the magnitude of the voltage surge drops below a first preselected level if the voltage appearing on the capacitor of the oscillatory circuit is above a second preselected level.

Claim 7

The suppressor as specified in claim 4 wherein said triggering means comprises first means for providing a first signal which is a function of the instantaneous magnitude of the surge, second means coupled to said oscillatory circuit capacitor for providing a second signal whenever the voltage on said capacitor is above said second preselected level and third means coupled to said first and second detector means for rendering said switch conductive whenever the second signal exceeds the first signal by a preestablished value.

Claim 8

In an electrical system for supplying D-C power from a voltage source to an electrical load, a solid state surge suppressor connected across said voltage source for arresting surges in the system while limiting such surges to a predetermined maximum, said suppressor comprising: a. non-linear resistance means having a negative current-resistance characteristic; b. a normally non-conductive thyristor connected in series with said non-linear resistance means, said thyristor being rendered conductive in automatic response to the existence of a surge in said system; c. first triggering means operative in response to the presence of a surge for providing a trigger signal to render said thyristor conductive, said triggering means comprising: i. frequency dependent attenuating means, having an input and an output, for attenuating a voltage provided at its input which represents the voltage across said series circuit to provide an output voltage at said output, the degree of attenuation of said input voltage decreasing as the rate of rise of the input voltage increases, said attenuating means comprising a resistor composed voltage divider connected in parallel with a capacitor composed voltage divider, the values of the resistors and capacitors in said attenuating means being such that the degree of attenuation for a fast rising input voltage is slightly less than the degree of attenuation for a slow rising input voltage; and ii. level sensitive means coupled to the output of said voltage dividing means for providing said trigger signal when the attenuated output voltage reaches a preestablished level; and d. automatic means for causing said first thyristor to cease conducting comprising: i. an oscillatory circuit including a capacitor and an inductor connected in shunt with said thyristor via a normally non-conductive electric switch; and ii. second triggering means for rendering said electric switch conductive when the magnitude of the surge drops below a first preselected level if the voltage appearing on the capacitor of the oscillatory circuit is above a second preselected level.

Claim 9

In an electrical system for supplying D-C power from a voltage source to an electrical load, a solid state surge suppressor connected across said voltage source for arresting surges in the system while limiting such surges to a predetermined maximum, said suppressor comprising: a. non-linear resistance means having a negative current-resistance characteristic; b. a normally non-conductive thyristor connected in series with said non-linear resistance means, said thyristor being rendered conductive in automatic response to the existence of a surge in said system; c. first triggering means operative in response to the presence of a surge for providing a trigger signal to render said thyristor conductive, said triggering means comprising: i. frequency dependent attenuating means, having an input and an output, for attenuating a voltage provided at its input which represents the voltage across said series circuit to provide an output voltage at said output, the degree of attenuation of said input voltage decreasing as the rate of rise of the input voltage increases, said attenuating means comprising a resistor composed voltage divider connected in parallel with a capacitor composed voltage divider, the values of the resistors and capacitors in said attenuating means being such that the degree of attenuation for a fast rising input voltage is slightly less than the degree of attenuation for a slow rising input voltage; and ii. level sensitive means coupled to the output of said voltage dividing means for providing said trigger signal when the attenuated output voltage reaches a preestablished level; and d. automatic means for causing said first thyristor to cease conducting comprising: i. an oscillatory circuit including a capacitor and an inductor connected in shunt with said thyristor via a normally non-conductive electric switch; and ii. second triggering means for rendering said electric switch conductive when the magnitude of the surge drops below a first preselected level if the voltage appearing on the capacitor of the oscillatory circuit is above a second preselected level.

Claim 10

The suppressor as specified in claim 6 wherein the degree of attenuation for a fast rising input voltage is approximately 80% of the degree of attenuation for a slow rising input voltage.

Claim 11

The suppressor as specified in claim 6 wherein said second triggering means comprises first means detector for providing a first signal which is a function of the instantaneous magnitude of the surge, second means coupled to said oscillatory circuit capacitor for providing a second signal whenever the voltage on said capacitor is above said second preselected level and third means coupled to said first and second means for rendering said switch conductive whenever the second signal exceeds the first signal by a preestablished value.