Electric arc welding power supply
US4071885A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 5, 1975 |
| Grant date | Jan 31, 1978 |
| Priority date | — |
| Expiry date | Dec 5, 1995 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB23K9/1056
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.