Differential current fault protection for a system utilizing a power conversion unit exhibiting balanced load characteristics
US5521787A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1993 |
| Grant date | May 28, 1996 |
| Priority date | — |
| Expiry date | Jul 28, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/34
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A system of protection which utilizes a simple circuit for the detection and isolation of single and multiple phase to phase and phase to neutral faults between a multi-phase source of electrical energy and a power conversion device driven therefrom. The circuit comprises a current transformer positioned at the neutral aspect of each phase winding of the multi-phase source of electrical energy. These current transformers sense the current generated by the source of electrical energy and produce a signal of proportional magnitude thereby. These proportional sense signals from each of the individual current transformers are transmitted to a controller which vectorially adds these signals to produce a single summed output signal. The controller monitors the percent ripple content of the summed output signal and generates an output protection signal if the percent ripple content of the monitored summed output signal exceeds a predetermined threshold value for a predetermined time interval. Means are provided responsive to the output protection signal for de-energizing the multi-phase source of electrical energy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.