A power tool comprises a housing and an electric motor disposed in the housing. A rotary output is driven by the motor. Electronic sensor configured to sense operating parameters of the power tool includes a voltage sensor arranged to detect the voltage across the electric motor, a current sensor arranged to detect the current through the tool, and a speed sensor arranged to detect the angular velocity ω of the output spindle. Electronic control apparatus is configured to determine from the operating parameter output signals the torque M of the rotary output and control the angular velocity of the rotary output in response to the calculation of the torque of said rotary output.

Method for protecting an electric motor of a motor driven consumer equipped with a controller for controlling the capacity or the power of the consumer, comprises the following steps: the determination of the thermal condition of the motor by direct measurement on the motor; and the limitation of the maximum capacity or the maximum power of the consumer as a function of the aforementioned determined thermal condition.

A motor drive apparatus includes a control assembly that controls driving of a motor. The control assembly includes a controller that outputs a drive signal instructing a drive amount of the motor, a drive that supplies electric current, supplied from an external power supply, to the motor based on the drive signal output from the controller, a current detector that detects electric current flowing through the drive unit, and a first temperature detector that detects temperature of the drive unit. The control assembly calculates a heat storage amount stored in the control assembly at a predetermined cycle, and when the calculated heat storage amount is larger than a predetermined threshold, the control assembly outputs the drive signal that instructs a drive amount smaller than the drive amount at the time of calculation.

A power tool comprises a housing and an electric motor disposed in the housing. A rotary output is driven by the motor. Electronic sensor configured to sense operating parameters of the power tool includes a voltage sensor arranged to detect the voltage across the electric motor, a current sensor arranged to detect the current through the tool, and a speed sensor arranged to detect the angular velocity of the output spindle. Electronic control apparatus is configured to determine from the operating parameter output signals the torque M of the rotary output and control the angular velocity of the rotary output in response to the calculation of the torque of said rotary output.

Method for protecting an electric motor of a motor driven consumer equipped with a controller for controlling the capacity or the power of the consumer, comprises the following steps: the determination of the thermal condition of the motor by direct measurement on the motor; and the limitation of the maximum capacity or the maximum power of the consumer as a function of the aforementioned determined thermal condition.

The invention relates to a device and to a method for monitoring an electrical network in a rail vehicle. The electrical network includes at least one converter, at least one drive motor, at least one first phase line for electrical connection of the at least one converter and the at least one drive motor. A magnitude of a current change of a first phase current is determined. A network error in a partial network on the machine side is detected if at least one criterion based on the current change is met. The criterion based on a current change is met when the magnitude of the current change of the first phase current is greater than a predetermined current change threshold.

The invention relates to a device and to a method for monitoring an electrical network in a rail vehicle. The electrical network includes at least one converter, at least one drive motor, at least one first phase line for electrical connection of the at least one converter and the at least one drive motor. A magnitude of a current change of a first phase current is determined. A network error in a partial network on the machine side is detected if at least one criterion based on the current change is met. The criterion based on a current change is met when the magnitude of the current change of the first phase current is greater than a predetermined current change threshold.

The invention relates to a demolition robot (1), comprising a cable (12) intended to be connected to an electric network to power a motor (21), a pump (22) that is powered by the electric motor for generating a hydraulic flow to consumers (13), wherein the motor (21) is activable at varying thermal load values (PT), depending on the current consumer's (13) need for hydraulic power, a control unit (24) arranged to receive information about the thermal load (PT) on the motor, to determine a partial thermal damage value (SL, SM, SH) at various thermal loads (PT) on the motor. To minimize the risk of thermal damage to the motor, the control unit (24) is adapted to compare said partial thermal damage values (SL, SM, SH) with a normative partial thermal damage (A) and is adapted to limit the thermal load (PT) on the motor (21) to a maximum allowable thermal load value (PTmax), if the partial thermal damage value (SL, SM, SH) exceeds the normative partial thermal damage (A) at a predetermined value (A).