Electromagnetic pulse isolation transformer

An isolation transformer for connection between a source of alternating current power and electronic components, the operation of which components is adversely affected by voltage excursions occasioned by electromagnetic pulses, said transformer comprising:

• a ferromagnetic core including a first end, a second end and at least two legs extending intermediate said ends and defining therewith at least one window in said core;
• a primary coil surrounding a first portion of said core and extending through a said at least one window in said core;
• a secondary coil, spaced from said primary coil, surrounding a second portion of said core and extending through a said at least one window in said core;
• a metallic isolation shield disposed between said primary coil and said secondary coil, said shield having core apertures for receiving components of said core so that said shield passes through each window of said core;
• a first metallic housing mounted on said shield and having an opening for receiving said primary coil and the portion of said core on the primary coil side of said shield;
• and
• an electrically conductive first foil wrapped about and insulated from said primary coil and electrically connected to said housing so that said housing, said shield and said foil form a first Faraday cage, said primary coil having leads passing through said foil and outside said housing with said shield extending beyond said housing to form a mounting flange for said transformer.

An isolation transformer system for connection between a source of alternating current power and electronic components, the operation of which components is adversely affected by voltage excursions caused by electromagnetic pulses, said system comprising an enclosure for said electronic components having a metallic wall with an opening therethrough, said system further including an isolation transformer comprising:

• a ferromagnetic core including a first end, a second end and at least two legs extending intermediate between said ends and defining therewith at least one window in said core;
• a primary coil surrounding a first portion of said core and extending through a said at least one window in said core;
• a secondary coil, spaced from said primary coil, surrounding a second portion of said core and extending through a said at least one window in said core;
• a metallic isolation shield disposed between said primary coil and said secondary coil, said shield having core apertures for receiving components of said core so that said shield passes through each window of said core;
• a first metallic housing mounted on said shield and having an opening receiving said primary coil and the portion of said core on the primary winding side of said shield;
• an electrically conductive first foil wrapped about said primary coil and insulated therefrom and electrically connected to said housing so that said housing, said shield and said foil form a Faraday cage, said primary coil having leads passing through said foil and outside said housing with said shield extending beyond said housing to form a mounting flange for said transformer, said flange being fastened to material defining the opening in said wall of said enclosure.

An isolation transformer for connection between a source of alternating current power and electronic components, the operation of which is adversely affected by voltage excursions caused by electromagnetic pulses, said transformer comprising:

• a ferromagnetic core defining at least one window;
• a primary coil surrounding a first portion of said core and extending through a said at least one window in said core;
• a secondary coil spaced from said primary coil, surrounding a second portion of said core and extending through a said at least one window in said core;
• a metallic wall, which forms a part of an enclosure for said electronic components, disposed between said primary coil and said secondary coil, said wall having core apertures for receiving components of said core so that said wall passes through each window of said core;
• a metallic housing mounted on said wall and receiving said primary coil and the portion of said core on the primary coil side of said wall;
• and
• an electrically conductive foil wrapped about and insulated from said primary coil and electrically connected to said housing so that said housing, said wall and said foil form a first Faraday cage, said wall forming an isolation shield for said transformer.