| 摘要 |
In the manufacture of electrical coils (10), particularly large transformer coils, an insulated wire (11) is wound on a rotatable winding arbor (12) so as to form a succession of turns of the insulated wire. Particularly when large gauge enamelled copper wire is wound, the insulation (14) has a tendency to crack or chip during the winding process, causing shorted turns and producing a defective coil. This disclosure relates to systems for testing such a coil to detect a short as it is wound so as to permit interruption of the winding process and repair of the insulation fault on the spot. The test equipment includes a pair of test windings (41, 42) positioned at opposite ends of the winding arbor (12) and magnetically coupled by flux paths (50, 51) to each other and to the coil being wound so that an A.C. input signal (V1) applied to the first winding (41) induces an A.C. output signal (V2) in the second winding (42) that undergoes a characteristic change, such as a voltage drop, when a short occurs. A detecting circuit (60) senses such a change in the output signal and provides an output (63) when a shorted turn is detected. Preferably, a parallel shunt return path (70) is provided between the arbor and the machine frame so as to increase the sensitivity of the detector circuit.
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