The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 12, 1978
Filed:
Sep. 21, 1977
John C Lewis, Wentworth, CA;
Park-Ohio Industries, Inc., Cleveland, OH (US);
Abstract
An auxiliary electrical test circuit is provided which is adapted to assist in matching the resonant frequency of an induction heating load with the rated frequency range of a solid state high frequency power source coupled to the load circuit. The load circuit includes an inductor, power factor correction capacitors, and a given workpiece to be inductively heated. The test circuit includes an audio frequency oscillator of low output power having an output frequency which may be adjusted in a range extending below and above the rated frequency range of the solid state power source. The oscillator output is coupled to the load circuit independent of the solid state power source, and the output frequency of the oscillator is adjusted to coincide with the resonant frequency of the load circuit, which coincidence is determined by observing the peak voltage obtained during adjustment of the oscillator output frequency. The oscillator frequency is then compared to the rated frequency range for the solid state power supply. If the resonant frequency of the load circuit is outside the rated frequency range for the solid state power supply, power factor correction capacitors are added or subtracted until the load circuit frequency is determined to be within the rated frequency range of the power supply.