ELECTROMAGNETIC FILTER

PURPOSE:To provide an electromagnetic filter of small power consumption and low running cost, by connecting a controlling means, used for changing the magnetic force of a magnetic material which is magnetized by an exciting coil, to the exciting coil. CONSTITUTION:A perforated plates 2 made of magnetic materials are arranged at the upper and lower sides in the inside of a filtering tower 1 made of stainless steel plate, and steel balls and steel wire-nets made of magnetic materials are packed between the plates 2 to constitute a magnetic filter-layer 3. A return frame 4 is provided to the outside of the tower 1 by surrounding the layer 3, and an exciting coil 5 is arranged in the inside of the frame 4. A controlling means 7 is provided to the place between an electric power source 6 and the coil 5 to gradually enhance the intensity of an impressed magnetic field and stengthen a magnetic force by the controlling means 7 during running, that is, through the period of initial, intermediate, and final stages of water passing. The controlling means 7 is used for changing an electric current value to be supplied to the exciting coil stepwise or in a stepless state, or changing the number of turns of the exciting coil substantially.