INPUT-CURRENT DETECTING CIRCUIT USING CURRENT TRANSFORMER

摘要

PROBLEM TO BE SOLVED: To constitute the circuit of a low-lost circuit and to secure the constant detecting accuracy without depending on the accuracy of constituting elements. SOLUTION: The unput current of the reference current value of Is=10A is made to flow to the primary side of a current transformer CT (S1). The reference-current pickup value Im is obtained (S2). A current ratio Is/Im is computed (S3). The current ratio Is/Im is written into an E<2> PROM (S4). The current ratios are different for every circuits. By multiplying the current ratio stored in the E<2> PROM on a current-value read value Iy by a microcomputer, the input current I can be accurately detected.