Protection circuit against electric shocks during welding
US4514615A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 1984 |
| Grant date | Apr 30, 1985 |
| Priority date | — |
| Expiry date | Apr 23, 2004 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB23K9/10
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A circuit for controlling the power supply to an electrode of the shielded type, such as that used in a shielded metal arc welding process (SMAW) whereby to protect a user from electric shocks. The control circuit is a protection circuit which serves to protect welders against electric shocks by decreasing the circuit voltage between the electrode tip and the workpiece to be welded. An AC or DC power supply may be used to feed the electrode. The control circuit is comprised of a high impedance voltage source applied to the electrode, a detection circuit for determining the level value of the impedance appearing between the electrode and the workpiece. The detection circuit compares the impedance thus detected with a threshold impedance and generates a control signal when the detected impedance is lower than the threshold impedance. The control signal operates a driver circuit which energizes a power feed device serially connected between the electrode power supply and the electrode itself. The predetermined threshold impedance value is set at about 500 ohms whereby a wet human body will not be subjected to an electric shock by contacting the electrode and the workpiece simultaneous…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.