Apparatus including an oscillator for detecting faults in coil windings and having means for comparing the frequency and amplitude of the oscillator output signal

Claim 1

APPARATUS FOR DETECTING FAULTS IN COILS WOUND ON PARAMAGNETIC METAL CORES COMPRISING, IN COMBINATION, AN OSCILLATOR HAVING A RESONANCE CIRCUIT INCLUDING AN INDUCTANCE AND A CAPACITANCE AND DETERMINING THE OSCILLATOR OUTPUT SIGNAL FREQUENCY; MEANS APPLYUING AN OPERATING POTENTIAL TO SAID OSCILLATOR; SAID OSCILLATOR HAVING AN OUTPUT; CONVERTER MEANS AHVING AN INPUT CONNECTED TO THE OUTPUT OF SAID OSCILLATOR AND OPERABLE TO PRODUCE A FIRST D.C. OUTPUT VOLTAGE CORRESPONDING SOLELY TO THE FREQUENCY OF THE OUTPUT SIGNAL OF SAID OSCILLATOR; RECTIFIER MEANS HAVING AN INPUT CONNECTED TO THE OSCILLATOR OUTPUT IN PARALLEL WITH THE INPUT OF SAID CONVERTER MEANS, AND OPERABLE TO PRODUCE A SECOND D.C. OUTPUT VOLTAGE CORRESPONDING SOLELY TO THE AMPLITUDE OF THE OSCILLATOR OUTPUT SIGNAL; A COMPARISON BRIDGE HAVING FIRST AND SECOND INPUTS; MEANS FOR IMPRESSING SAID FIRST D.C. OUTPUT VOLTAGE ON SAID FIRST INPUT AND FOR IMPRESSING SAID SECOND D.C. OUTPUT VOLTAGE ON SAID SECOND INPUT; AND MEANS FOR BALANCING SAID BRIDGE WHEN SAID OSCILLATOR IS OPERATIVE; WHEREBY, WHEN A FAULTY COIL WOULD ON A PARAMAGNETIC METAL CORE IS PLACED ADJACENT THE INDUCTANCE OF THE RESONANCE CIRCUIT OF SAID OSCILLATOR, THE ABSORPTION OF OSCILLATOR ENERGY DUE TO EDDY CURRENT LOSSES IN THE PARAMAGNETIC METAL CORE AND DUE TO SAID FAULT WILL EFFECTIVELY REDUCE THE OUTPUT POTENTIAL OF SAID OSCIALLTOR AND THE DECREASE IN INDUCTANCE OF THE RESONANCE CIRCUIT OF SAID OSCILLATOR, DUE TO THE COIL PLACED ADJACENT THE INDUCTANCE OF THE LATTER, WILL INCREASE THE OSCILLATOR OUTPUT FREQUENCY, TO EFFECIVELY UNBALANCE SAID COMPARISON BRIDGE WHEREBY TO INDICATE A FAULT IN SAID COIL WOUND ON SAID PARAMAGNETIC METAL CORE.