| 摘要 |
<p>PURPOSE:To secure an insulating property and noise resistance and to measure a current over a range from a large current to a small current with high accuracy, by providing secondary winding to a magnetic core and shortcircuiting the same through a resistor smaller than exciting impedance. CONSTITUTION:Secondary and tertiary windings 2, 3 are wound around a ring-shaped magnetic core 1 through which a primary conductor L pierces and a resistor 4 smaller than exciting impedance is connected to the output terminal of the winding 2. An optical voltage sensor 5 using an electro-optical effect element is connected to the winding 3 and the current I flowing to the conductor L from the sensor 5 is measured. Since the winding 2 is provided to the core 1 and shortcircuited by the resistor 4 smaller than the exciting impedance, back electromotive force is generated in the winding 2 and the magnetic saturation of the current I flowing to the conductor L is avoided in the winding 2 and highly accurate measurement can be performed even in a large current region. Since the sensor 5 can be measured in such a state that output voltage is amplified by changing the number-of-winding ratio of the windings 2, 3, a sufficient S/N ratio is obtained and highly accurate measurement can be performed even in a small current region.</p> |
