| 摘要 |
A method and apparatus for composing a desirable trip curve, such as an I2*t trip curve, for an electrical protective device from at least one less desirable trip curve, such as an I*t trip curve. The method is accomplished by defining a selected parameter of the desirable overload trip curve and defining the selected parameter as a function of one or more monitored input values, such as current, trip class or phase unbalance, and modulating the selected defined parameter value between a maximum boundary trip curve and a minimum boundary trip curve. The modulated parameter is used to adjust the less desirable trip curve such that it has the characteristics of the desired trip curve. The method is implemented by one or more electrical circuits (filter circuits) representing the less desirable trip curve(s) and composing an output signal representing the desirable trip curve by modulating between the one or more electrical circuits. |
