Apparatus for testing the integrity of an electrical coil as it is wound

Apparatus for winding an electrical coil of insulated wire and for testing the coil for shorted turns as it is wound, which comprises:

• a machine frame;
• a rotatable winding arbor;
• means for mounting the arbor for rotation in the frame about a longitudinal winding axis;
• a drive motor for rotating the arbor so as to wind the insulated wire on winding surface of the arbor in a series of consecutive turns to form the coil;
• an input test winding fixedly mounted to the machine frame coaxially adjacent to one end of the arbor;
• a pickup test winding fixedly mounted to the machine frame coaxially adjacent to the other end of the arbor;
• means for applying an A.C. input signal to the input winding;
• means for establishing a magnetic flux path through the arbor and adjacent portions of the winding apparatus, for coupling the windings to each other and to the coil being wound so that the input signal induces an A.C. output signal in the pickup winding having a nominal steady-state voltage when the coil being wound is not shorted and a characteristically lower voltage when a short occurs;
• and
• means for sensing a characteristic drop in the output voltage for indicating a short in the coil and for stopping the drive motor when a short is detected so as to permit repair of the fault, following which the winding operation may be resumed.

Apparatus for testing the integrity of an electrical coil including turns of an insulated wire being wound on a core member, which comprises:

• a first test winding positioned adjacent to one side of the coil being wound;
• a second test winding positioned adjacent to the other side of the coil being wound;
• means for applying an A.C. input signal to the first test winding;
• means for magnetically coupling the test windings to each other and to the coil being wound so that the input signal induces in the second winding an A.C. output signal having a nominal steady-state voltage when the coil is not shorted and a characteristically different voltage when a short occurs;
• and
• means for detecting such a characteristic change in the output voltage to provide an indication that the turns being wound are shorted, said detecting means including an A.C. bridge detector circuit including a differential comparator and means for connecting the first and second test windings to the circuit so that the comparator normally provides an output of essentially zero volts when the coil being wound is continuous, and so that a voltage rise is generated at the comparator when a short occurs.