A switching device protects an electrical load against overcurrent. A load current path from a current source to the load is connected through a semiconductor switch. In the on-state of the switch, the current is permitted to flow. In the off-state, the load current is blocked. A control circuit is configured to switch the semiconductor switch in response to a switching signal. The current in the load current path is measured. A controller execute an individual function or a combination of two or more predefined functions depending on an operating mode of the electrical load. The functions compare a current intensity and/or a temporal current profile of the current through the load current path with defined threshold values. The control circuit is driven by the switching signal that depends on one or more results of the executed functions to selectively switch off the semiconductor switch.

A combination electric tool includes a main body and at least one working part drivable via and separably attachable to the main body. The main body includes an electric motor and a control circuit with a signal recognition module having a microcontroller. The working part includes an identification module, the signal recognition module and the identification module being communicable such that the microcontroller can recognize the working part. A control method includes attaching the main body to the working part; judging which kind of working part is attached and selecting corresponding preset programs; sampling a working parameter value of the electric motor; comparing the sampled working parameter value of the electric motor with a corresponding preset value, and judging whether the electric motor is at an abnormal working state; and if yes, powering off the electric motor, and if no, returning to the previous step.

A hand-held electrically powered cut-off tool (100) for cutting concrete and stone by a rotatable cutting disc (105), the cut-off tool (100) comprising an electric motor (130) arranged to be controlled by a control unit (110) via a motor control interface (120), wherein the control unit (110) is arranged to obtain data indicative of an angular velocity of the cutting disc (105), and to detect a kickback condition based on a decrease in angular velocity, wherein the control unit (110) is arranged to control an electromagnetic braking of the electric motor (130) in response to detecting a kickback condition, wherein the control unit (110) is arranged to determine an angular acceleration associated with the electric motor (130), and to detect the kickback condition based on a comparison between the determined angular acceleration and a configurable detection threshold.