Patent ID: 8717032

Claim:
An electronic circuit breaker for use in a power supply distribution system, comprising: at least one protection switch in the form of a controllable semiconductor arranged to conduct current through the power supply line in a normal mode and to limit the current if an error occurs which causes the current to increase above an upper threshold level, a control unit arranged to control the at least one protection switch to enter a test mode in which the current through the at least one protection switch is reduced compared to the normal mode, a registration unit arranged to register during test mode a test mode value of at least one electrical characteristic in the power supply line that will be affected when the test mode is applied, and a monitoring unit arranged to evaluate the at least one electrical characteristic and determine, based on the evaluation, whether or not the protection switch is malfunctioning and to take an action if it is determined that the protection switch is malfunctioning, wherein the registration unit is arranged to register a normal mode value of the at least one electrical characteristic during normal mode and the monitoring unit is arranged to evaluate the electrical characteristic by comparing the test mode value to the normal mode value.