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. 31, 1978
Filed:
Dec. 05, 1975
Dale Louis Bilczo, Parma Heights, OH (US);
Kenneth Anthony Golonka, Richmond Heights, OH (US);
John Arthur Overman, Chagrin Falls, OH (US);
John Ernest Carroll, Moreland Hills, OH (US);
The Lincoln Electric Company, Cleveland, OH (US);
Abstract
A three phase electric arc welding power supply using SCR rectifiers for output control which has improved output characteristics, fault protection and current and voltage controls. The main power transformer includes two secondaries connected in a double wye with the neutral points supplying power to one of the output terminals a pair of independent inductances are in series, one with each set of secondaries. Increased phaseback of the SCR's may be effected without the use of additional inductance in the output circuit. The fault protection circuit has a time-current trip curve closely approximating the time-current overload curve of the SCR's whereby the minimum size SCR's for a given maximum current output is obtained. The control circuit is fast responding and gives either: constant voltage output; or variable voltage, constant current output with both line voltage compensation and with increase of current when the arc is shorted and the arc voltage drops below a predetermined amount. Improved firing circuits for the main and pilot SCR's are provided.