Patent ID: 8319465

Claim:
A method for automatic setting of a protective device including an overcurrent release, the protective device having an asynchronous motor as a load to be protected against overloading, the protective device protecting the power distribution installation against short-circuiting, wherein at least one tripping time has to be set as a parameter on the overcurrent release, to ensure that no thermal overloading of the asynchronous motor occurs, the method comprising: determining the integral of the square of the motor current over time on the basis of the time motor current profile of the asynchronous motor on a load, after switching on and reversing; and deriving the tripping time of the overcurrent release on the basis of the determined integral, the integral, which corresponds to the heating of the asynchronous motor, being related to a multiple of the square of the rated current, and the motor current profile including at least the starting current, the transient and the selected motor rated current.