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. 06, 1983
Filed:
May. 14, 1982
Steven H Verhoff, Toledo, OH (US);
David A Krieger, Toledo, OH (US);
Midland-Ross Corporation, Cleveland, OH (US);
Abstract
An electrically heated vacuum furnace is described as having a fault detection system which has the ability to sense among other things, carbon arc buildup, a load touching a heating element, short circuits from broken heating elements, and short circuits in any heating element connection whether it be single phase, three phase delta or three phase wye connections. The system essentially comprises an electrically balanced wheatstone bridge which is in a main circuit in parallel with the electric heating element and the grounded casing of the furnace. A switching mechanism maintains the circuit in a normally open condition. A timer is provided to periodically disrupt the flow of electric current to the electric heating element in the furnace. The switching mechanism will be operated to close the circuit if the circuit is free of electric current. Should any of the aforementioned faults occur, the bridge will be thrown out of balance so that there will be a small leakage of current which is detected and utilized in the shutting down of the furnace in cases where the fault is severe and necessitates stopping the operation of the furnace.