Ground fault protection method and apparatus
US6347025B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 21, 2000 |
| Grant date | Feb 12, 2002 |
| Priority date | — |
| Expiry date | Jan 21, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/52
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for supply welding, plasma cutting, and/or induction heating power having a ground fault interrupt (GFI) protection circuit is disclosed. The primary winding of a monitoring transformer in the GFI protection circuit is connected between the high frequency floating output of the power supply and ground. One end of the secondary of the monitoring transformer is connected to a voltage source. The other end of the secondary is connected to an impedance. The other end of the impedance is connected back to the voltage source to form a voltage divider across the voltage source. Changes in the impedance between the floating output of the power supply and ground are sensed by the GFI protection circuit and converted into a voltage. This voltage is filtered, rectified, and calibrated into a dc sense signal. The sense signal is compared to a threshold signal. In the event the sense signal exceeds the threshold signal, an interrupt signal is sent to the power supply and the power supply shuts down.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.