| 摘要 |
PURPOSE:To make it unnecessary to apply a common current to a main coil and a shielding coil and facilitate exciting the two coils by one exciting source by a method wherein permanent current switches are connected in parallel to the main coil and the shielding coil respectively and the main coil and the shielding coil are mutually connected in series and the exciting source is connected between both the ends of the series-connected unit. CONSTITUTION:A main coil 1 and a shielding coil 2 are mutually connected in series and a permanent current switch 6a is connected in parallel to the main coil 1 and a permanent current switch 6b is connected in parallel to the shielding coil 2. Although the main coil 1 and the shielding coil 2 are connected in series like this, the main coil 1 and the shielding coil 2 constitute individual circuit with the permanent current switches 6a and 6b respectively during a normal operation. Therefore, the main coil 1 and the shielding coil 2 can be driven by different currents. Moreover, current leads 7, an exciting source 10 and the like can be used in common. |
