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:
Jan. 11, 1977
Filed:
Mar. 03, 1976
John F Wolfinger, Schenectady, NY (US);
General Electric Company, Schenectady, NY (US);
Abstract
Method and apparatus for applying controlled electromagnetic force to a test specimen such as a turbine bucket to induce vibration in the specimen. The force is applied by means of an electromagnetic field produced by an electromagnet. A controlled power source supplies current to the electromagnet to maintain the applied force at a predetermined magnitude over a predetermined range of frequencies. A comparator controls the power source in response to a sensor signal representative of the frequency and magnitude of the face actually applied so as to maintain at a minimum the difference between this signal and a reference signal representative of a desired frequency and magnitude. Tuning means are provided to nullify capacitive reactance of the electromagnet which would otherwise tend to limit the current supplied by the power source as frequency is increased.