Circuit breaker device and method of triggering the circuit breaker device if current and voltage threshold values are exceeded in a time window

1 . A circuit breaker for protecting an electrical low-voltage circuit having conductors, comprising:

a housing having connections for the conductors of the electrical low-voltage circuit;

a current sensor to ascertain a level of a current of the electrical low-voltage circuit, with a result that current values are available;

a voltage sensor to ascertain a level of a voltage of the electrical low-voltage circuit, with a result that voltage values are available;

an electronic interruption unit having semiconductor-based switching elements and, as a result of said semiconductor-based switching elements, said electronic interruption unit has a high-impedance state for said semiconductor-based switching elements for a purpose of interruption and a low-impedance state for said semiconductor-based switching elements for a purpose of current flow in the electrical low-voltage circuit;

a controller connected to said current sensor, to said voltage sensor and to said electronic interruption unit;

the circuit breaker is configured such that the current values are used to ascertain a change in current over time, with a result:

that current change values are available cyclically;

that the voltage values and an expected value for the voltage are used to ascertain a difference voltage, with a result that difference voltage values are available cyclically;

that each of the difference voltage values is compared with a first threshold value;

that each of the current change values is compared with a second threshold value; and

that the interruption of the electrical low-voltage circuit is initiated if the first and second threshold values are exceeded within a first time window.

2 . The circuit breaker according to claim 1 , further comprising a mechanical isolating contact system connected in series with said electronic interruption unit, with a result that electrical isolation can be engaged in the electric low-voltage circuit, wherein said mechanical isolating contact system is connected to said controller.

3 . The circuit breaker according to claim 2 , wherein the electrical isolation is further initiated if the first and second threshold values are exceeded within the first time window.

4 . The circuit breaker according to claim 2 , wherein the electrical isolation is initiated if said electronic interruption unit is at high impedance and there is a current in the electrical low-voltage circuit that exceeds a third threshold value.

5 . The circuit breaker according to claim 4 , wherein the third threshold value is greater than 5 mA.

6 . The circuit breaker according to claim 1 , wherein the interruption of the electrical low-voltage circuit is initiated if at least two successive said difference voltage values have been exceeded.

7 . The circuit breaker according to claim 1 , wherein the interruption of the electrical low-voltage circuit is initiated if at least two successive said current change values have been exceeded.

8 . The circuit breaker according to claim 1 , wherein the current change values and the difference voltage values are available at a clock frequency that is greater than/equal to 10 KHz and less than/equal to 10 MHz.

9 . The circuit breaker according to claim 1 , wherein the second threshold value is in a range from 1 to 10 A/μs.

10 . The circuit breaker according to claim 1 , wherein the first threshold value is in a range from 10 to 100 V.

11 . The circuit breaker according to claim 1 , further comprising:

a first comparator having an output, wherein the difference voltage values are supplied to said first comparator to compare each of the difference voltage values with the first threshold value;

a second comparator having an output, the current change values being supplied to said second comparator to compare each of the current change values with the second threshold value; and

a first AND gate having an output, wherein said output of each of said first and second comparators are combined by way of said first AND gate, with a result that the interruption of the electrical low-voltage circuit is initiated if the first and second threshold values are exceeded.

12 . The circuit breaker according to claim 11 , further comprising:

a first buffer store;

a second buffer store;

a second AND gate having an output, said output of said first comparator is further connected to said second AND gate:

firstly directly;

secondly via said first buffer store, which buffer-stores precisely one comparator output value;

thirdly via said first buffer store in series with said second buffer store, which buffer-stores precisely one comparator output value, with a result that the interruption of the electrical low-voltage circuit is initiated if at least two said successive difference voltage values have been exceeded.

13 . The circuit breaker according to claim 12 , further comprising:

a third buffer store; and

a third AND gate having an output, wherein said output of said second comparator is further connected to said third AND gate firstly directly and secondly via said third buffer store, which buffer-stores precisely one comparator output value, with a result that the interruption of the electrical low-voltage circuit is initiated if at least two successive said current change values are exceeded.

14 . The circuit breaker according to claim 13 , further comprising an OR gate, wherein said outputs of said first, second and third AND gates are combined by way of said OR gate, with a result that the interruption of the electrical low-voltage circuit is initiated:

if the first and second threshold values are exceeded within the first time window; or

if at least two successive said difference voltage values are exceeded; or

if at least two successive said current change values are exceeded.

15 . A method for protecting an electrical low-voltage circuit, which comprises the steps of:

ascertaining a level of a current of the electrical low-voltage circuit, with a result that current values are available;

ascertaining a level of a voltage of the electrical low-voltage circuit, with a result that voltage values are available;

using the current values to ascertain a change in current over time, with a result that current change values are available cyclically;

using the voltage values and an expected value for the voltage to ascertain a difference voltage, with a result that difference voltage values are available cyclically;

comparing each of the current change values with a second threshold value;

comparing each of the difference voltage values with a first threshold value; and

initiating an interruption of the electrical low-voltage circuit by semiconductor-based switching elements, which are put into a high-impedance state, if the first and second threshold values are exceeded within a first time window.

16 . The method according to claim 15 , which further comprises initiating the interruption of the electrical low-voltage circuit by the semiconductor-based switching elements, which are put into the high-impedance state, if at least two successive said difference voltage values have been exceeded.

17 . The method according to claim 15 , which further comprises initiating the interruption of the electrical low-voltage circuit by the semiconductor-based switching elements, which are put into the high-impedance state, if at least two successive said current change values have been exceeded.

18 . The method according to claim 15 , wherein the semiconductor-based switching elements have a low-impedance state for a purpose of current flow in the electrical low-voltage circuit.

19 . The method according to claim 15 , which further comprises initiating electrical isolation if an electronic interruption unit is at high impedance and the current in the electrical low-voltage circuit exceeds a third threshold value.