This invention relates to a control device for digital-controlling and protecting switch appliances, in which, the primary module includes a
microprocessor, an on-line
programming circuit, a current detecting module includes
signal collectng and regulating circuit of a current
signal and zero-sequence current
signal, a parameter setting input module includes setting of
potentiometer, setting of DIP dialing and selecting switch and a
key switch, an output drive module includes outputting
solid relay drive control, an output display module includes a
diode display circuit, and the current signals of the current mutual-
inductor and that of the zero-sequence current mutual-
inductor are rectified and filtered to be sent to the
microprocessor for AD conversion to compute current value, the parameter setting circuit sets the parameter signal and sends it to the
microprocessor to be stored and analyzes the collected signals to judge the state of the load and fault to
cut the primary circuit by outputting the drive
control circuit, the
software of the control device includes a primary process and the combination of related sub-process and hardware.