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AssigneeRIT Research Corp.
InventorRonald B. Standler
Estimating the term…
Overvoltage protection devices operative to prevent damage to electrical equipment in response to overvoltages in the form of fast transients and also to continuous overvoltages utilizes clamping or discharge elements which conduct in response to overvoltages or current surges. A high voltage responsive element, suitably a spark gap, is connected to the input of the device which goes to the line, while a lower voltage responsive element, suitably an avalanche diode or diodes or a zener diode or diodes, is connected to the output of the device which goes to the equipment to be protected. A resistor is connected between the spark gap and the avalanche device in series with one side of the line on the circuit to be protected. This resistor is preferably a positive temperature coefficient resistor which changes resistance rapidly to a high resistance state when the avalanche device conducts so as to protect the avalanche device while allowing the development of overvoltages sufficient to cause breakdown and conduction in the spark gap. Fast overvoltage transients are protected against by inductance between the avalanche device and the output that is greater than the inductance in the shunt path provided by the avalanche device.
An overvoltage protection device for overvoltages which appear on a line connected to the input of the device, which line transmits signals with respect to an electrical circuit connected to the output of said device, said protection device comprising an element having a resistance which decreases when an overvoltage is present on said line to a value much less than the resistance presented by said circuit to said output, said element being connected in shunt with said line across said output, and means presenting an inductive reactance greater than the inductive reactance presented to said line by said element and of sufficient magnitude to enable the resistance of the element to decrease to said much less value before said overvoltage reaches the output of said device and said electrical circuit connected thereto, said inductive reactance presenting means being connected between said element and said output.
In a transient overvoltage protective device having a breakdown element and a clamping element operative to breakdown at higher and lower voltages, respectively, said breakdown element being connected in shunt with the input of said device which is adapted to be connected to a signal line, and said clamping element being connected in shunt with the output of said device to the circuit to be protected, a pair of transmission circuits in series with said input and output and between said breakdown and clamping elements, said transmission circuits being in parallel with each other at least one of said transmission circuits being a low frequency transmission circuit comprising an inductor in series with a positive temperature coefficient resistor and the other being a high frequency transmission circuit comprising a capacitor.
Dependencies are inferred from the claim text.