| 摘要 |
<p>PURPOSE:To make an abnormality detecting sensor unnecessary, and detect even slight abnormality by estimating the abnormality of a system to be controlled based on the present value of the output of the system to be controlled and the information of a set value and necessary manipulated variable to the system to be controlled. CONSTITUTION:The necessary manipulated variable is calculated by an arithmetic circuit 4 based on the output and the set value of an electric furnace 1, and is sent to the electric furnace 1. On the other hand, the present value, the set value, and the necessary manipulated variable are inputted to an abnormality decision part 11, and here, the changing portions of the present value, the set value, and the necessary manipulated variable are detected by each differentiation circuit, and it is discriminated respectively whether each output lies within a definite range determined by high reference voltage and low reference voltage or exceeds said range or does not reach said range by a comparison circuit, and the outputs corresponding to results are sent. Then, a decoder circuit converts the extent of the abnormality into a decimal number from each output of the comparison circuit, and outputs it.</p> |
