Electronically commutated motor

An electronically commutatable motor having excitation windings, comprising:

• at least one semiconductor output stage;
• an electronic control unit controlling the excitation windings via the at least one semiconductor output stage by emitting control signals corresponding to an adjustable control signal and a setpoint value, the electronic control unit further storing a motor characteristic curve from which an assigned nominal operating speed is derivable for the setpoint value, the derived nominal operating speed being comparable to an actual speed of the motor;
• wherein, if a predefined speed difference between the nominal operating speed and the actual speed is exceeded, at least one of the electronic control unit and the at least one semiconductor output stage can be switched off, and
• wherein the motor characteristic curve is stored as a characteristics field having four three-dimensional corner points, each representing operating speeds of a characteristics field for a predefined, constant load, the corner points being determined by limiting values of a supply voltage and limiting values of the control signals, lines connecting the four corner points of the characteristics field permitting formation of a grid, from which, for an existing supply voltage and a control signal corresponding to the predefined setpoint value, the nominal operating speed is derivable from comparison to the measured actual speed.