Vacuum contactor protector
US4104689A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 29, 1976 |
| Grant date | Aug 1, 1978 |
| Priority date | — |
| Expiry date | Sep 29, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H33/668
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A circuit for detecting arcing in a vacuum contactor in a polyphase system, caused by development of an air leak. A current transformer and sensing means, which may be independent of or which may work in conjunction with a conventional ground fault relay, senses the unbalanced leakage current and activates warning and protection circuits so as to prevent damage to the rest of the system. The protection system is activated or switched into a higher sensitivity mode when the vacuum contactor is supposed to be open so as to detect relatively small leakage currents. When the vacuum contactor is supposed to be closed, the system is disabled or is operated in a lower sensitivity mode so as to detect ground faults, but so as not to be tripped by normal surges and transients during operation of the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.