| 摘要 |
PURPOSE:To minimize the error of overcurrent detection and the measured value of electrical various quantities by forming a current detector by two secondary side current transformers having two kinds of current transformation characteristics. CONSTITUTION:A core for a current transformer 21 installed to an electric wiring 10 is constituted by superposing a permalloy group core and a silicon steel plate group core so as to have two kinds of characteristics coinciding with the AC characteristics of a secondary side current transformer 23 and a secondary side current transformer 22. The current transformer 22 takes a general core type, and is formed by an silicon steel plate group core material. The current transformer 23 is shaped by a permalloy group core material. The combination of the current transformers 21 and 22 has high linearity in a high current region (accident currents), and the combination of the current transformers 21 and 23 has high linearity in a low current region (stationary currents). An output from the current transformer 22 is used for opening the detection 101 for accident currents and a contact 2, and output from the current transformer 23 is employed for the instrumentation 201 of electrical various quantities and display 301. Accordingly, the error of overcurrents and the measured values of electrical various quantities is minimized. |
