| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a small-sized CT(current transformer) having satisfactory output characteristics, at a low cost. SOLUTION: This circuit breaker is provided with a switching contact for a main circuit, a CT for detecting the load current, a rectifying circuit, a voltage converting element, a signal amplifying part, an A/D converting part, a CPU part for controlling tripping device, and a power source circuit. The CT is formed of a primary winding, a secondary winding, a bobbin part 20 for winding the secondary coil, a first core part 30 passing through the bobbin part 20, and a second core part 50 forming a closed magnetic circuit M.C with the first core part 30. The cross-sectional area of the second core part 50 crossing the magnetic flux direction is formed larger than the cross-sectional area of the first core part 30 at the same part, and magnetic resistance of the core part C is lowered without increasing the outline dimension of the CT as a whole, so as to improve the output characteristics of the CT.</p> |
