Circuit breaker and method

A circuit breaker device for protecting an electrical low-voltage circuit, the circuit breaker device comprising:

• a housing having network-side and load-side connections for conductors of the electrical low-voltage circuit;
• a voltage sensor for ascertaining a level of a voltage of the electrical low-voltage circuit;
• a current sensor for ascertaining a level of a current of the electrical low-voltage circuit;
• a mechanical isolating contact able to be operated using a mechanical handle and having contacts, with a result that opening of said contacts prevent a current flow or closing of said contacts for the current flow in the electrical low-voltage circuit is able to be switched;
• an electronic interruption unit connected in series with said mechanical isolating contact on a circuit side and having semiconductor-based switching elements, as a result of said semiconductor-based switching elements, said electronic interruption unit has a high-impedance state of said semiconductor-based switching elements to prevent the current flow and a low-impedance state of said semiconductor-based switching elements for the current flow in the electric low-voltage circuit;
• a controller connected to said voltage sensor, to said current sensor, to said mechanical isolating contact and to said electronic interruption unit, wherein if the current and/or current-time limit values is/are exceeded a process for preventing the current flow in the electrical low-voltage circuit is initiated;
• and
• the circuit breaker device is configured such that a user of the circuit breaker device operates said mechanical handle in order to close said contacts, wherein said electronic interruption unit is in the high-impedance state, in that, after said contacts have been closed, said electronic interruption unit goes to the low-impedance state only if a checking function allows the low-impedance state of said semiconductor-based switching elements.

A method for a circuit breaker device for protecting an electrical low-voltage circuit, which comprises the steps of:

• ascertaining a level of a current of the electrical low-voltage circuit;
• operating a mechanical isolating contact using a mechanical handle, with a result that opening of contacts to prevent a current flow or closing of the contacts for the current flow in the electrical low-voltage circuit can be switched;
• setting an impedance of an electronic interruption unit which is connected in series with the mechanical isolating contact on a circuit side and which, as a result of semiconductor-based switching elements, has a high-impedance state of the semiconductor-based switching elements in order to prevent the current flow and a low-impedance state of the semiconductor-based switching elements for the current flow in the electrical low-voltage circuit;
• comparing an ascertained level of the current with current and/or current-time limit values and if the current and/or current-time limit values are exceeded a process for preventing the current flow in the electric low-voltage circuit is initiated;
• and
• operating, via a user of the circuit breaker device, the mechanical handle in order to close the contacts, wherein the electronic interruption unit initially in the high-impedance state, and that, after the contacts have been closed, the electronic interruption unit goes to the low-impedance state only if a checking function allows the low-impedance state of the semiconductor-based switching elements.