Welding system and method utilizing a ground integrity monitor

• US 20040135589A1
• Filed: 05/22/2003
• Published: 07/15/2004
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: Matuschek Messtechnik GmbH
• Original Assignee: Matuschek Messtechnik GmbH
• Inventors: Poll, Karl, Usedom, Peter, Matuschek, Ulrich
• Granted Patent: US 6,914,440 B2
• Time in Patent Office: Days
• US Class Current: 324/691
• CPC Class Codes: B23K 37/006 Safety devices
• CPC Class Codes: B23K 9/10 Other electric circuits therefor; Protective circuits; Remote controls

Abstract

A welding system having a welding gun, comprising a casing that is grounded through a ground conductor, and a monitoring device, which detects the resistance of the ground conductor. A blanking device deactivates the monitoring device during the welding operation to reduce the danger of shut-downs through the ground integrity monitor. It is proposed to either deactivate the measuring circuit of the ground integrity monitor or to switch off the welding power interruption associated therewith as long as a welding current may flow or is flowing through the ground conductor. The monitoring device is deactivated or blanked out only for an essentially negligible fraction of the entire time, and there is no danger of any impairment of safety due to this short-term deactivation.

Claims

1. A welding system, comprising:

a welding gun having a casing, which is grounded through a ground conductor,

a monitoring device, which detects resistance of the ground conductor, and

a blanking device, which deactivates the monitoring device during a welding operation.

2. The welding system of claim 1, wherein the blanking device is positioned so that the monitoring device is deactivated during the time segments in which a welding current is being supplied.

3. The welding system of claim 2, further comprising a welding current controller, wherein a signal line is provided between the welding current controller and the blanking device, which during the time segments in which a welding current is being supplied, transmits a blanking signal to the blanking device.

4. The welding system of claim 2, further comprising several welding current controllers for the power supply to several welding guns, wherein a signal line leads to the blanking device, which during the time segments in which a welding current is being supplied from one of the welding current controllers, transmits a blanking signal to the blanking device.

5. The welding system of claim 1, wherein the blanking device is positioned so that the monitoring device is deactivated during the time segments in which a welding current flows through the ground conductor.

6. The welding system of claim 5, further comprising a current sensor, which detects the current flowing through the ground conductor.

7. The welding system of claim 1, wherein the monitoring device comprises a measuring system for measuring the voltage in the ground conductor, the voltage being generated in the ground conductor by a predetermined testing current.

8. The welding system of claim 7, wherein the measuring system comprises two inputs of the measuring system for voltage measuring, and the blanking device short-circuits said two inputs.

9. The welding system according to claim 1, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

10. The welding system according to claim 2, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

11. The welding system according to claim 3, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

12. The welding system according to claim 4, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

13. The welding system according to claim 5, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

14. The welding system according to claim 6, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

15. The welding system according to claim 7, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

16. The welding system according to claim 8, further comprising a transformer situated in the casing of the welding gun and having a primary winding and a secondary winding.

17. The welding system of claim 9, wherein the secondary winding of the welding transformer is grounded.

18. A method of monitoring the resistance of a ground conductor, which grounds a casing of a welding gun of a welding system, a power supply to the welding gun being interrupted in the event of excessively high resistance, wherein the monitoring of the ground conductor is deactivated during a welding operation.

19. The method of claim 18, wherein the monitoring of the ground conductor is deactivated during the time segments in which welding current is being supplied.

20. The method of claim 19, wherein a blanking signal is generated by a welding current controller during the time segments in which welding current is being supplied, and the monitoring of the ground conductor is deactivated during the appearance of the blanking signal.

21. The method of claim 19, wherein each of several welding current controllers in a welding system generates blanking signals during the time segments in which the particular welding current controller supplies welding current, and the monitoring of the ground conductor is deactivated during the appearance of one of said blanking signals.

22. The method of claim 18, wherein the monitoring of the ground conductor is deactivated during the time segments in which welding current flows through the ground conductor.

23. The method of claim 22, wherein the current flowing through the ground conductor is detected by a current sensor.

24. The method of claim 23, wherein the current sensor is a Hall sensor.

25. A method of monitoring the resistance of a ground conductor, comprising:

grounding a casing of a welding gun of a welding system with said ground conductor,

interrupting a power supply to the welding gun in the event of excessively high resistance in said ground conductor, and

deactivating the monitoring of the ground conductor during a welding operation.