Direct current solid state circuit breaker

Claim 1

A direct current circuit breaker for interrupting a direct current circuit when the current exceeds a programmable value, said circuit breaker using only solid state devices and comprising: a positive terminal and a negative terminal for connecting said circuit breaker in the direct current circuit to be controlled, said positive terminal and negative terminal being the only two terminals for connecting the circuit breaker into the direct current circuit; said circuit breaker being adapted so that a load may be connected common to either the positive or negative terminal of said circuit breaker; first means for generating a voltage drop including a solid state switch connected in series between said positive and negative terminals and through which the current being controlled normally flows; programmable voltage drop means connected in circuit with said first voltage drop means for generating a voltage drop equal to the voltage drop across said first voltage drop means said programmable voltage drop means being changeable within a range to change the value of the current at which said circuit breaker will interrupt the direct current circuit; solid state means to control whether said solid state switch is conductive or non-conductive, said solid state control means including solid state devices responsive to the voltage drop across the programmable voltage drop means; said solid state control means including a current source, said current source normally providing current for biasing said solid state devices to maintain said solid state switch in a conductive condition; said solid state means being connected to be responsive to the voltage drop across said programmable voltage drop means for diverting the biasing current from said solid state devices when the voltage drop exceeds a predetermined value to thereby make said solid state switch non-conductive; and said programmable voltage drop means and said solid state devices being connected to form a regenerative circuit for enhancing the turn-off time of said solid state switch.