Current sensing relay circuit with adjustable sensitivity and tracking test circuit
US4833564A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1987 |
| Grant date | May 23, 1989 |
| Priority date | — |
| Expiry date | Sep 24, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/006
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Ground fault interrupting circuit breaker (10) includes a sensing coil (20) which is the secondary winding of a current transformer having a core (18) and includes a test coil (22) also wound about the core with load conductors passing through the core. A current sensing circuit (30) compares the output from the sensing coil to a reference voltage which is adjustable to set the sensitivity of the breaker. A test circuit (42) generates in the test coil a test current whch has its magnitude determined by the same reference voltage which determines the sensitivity of the breaker, thus causing the test current to automatically track the sensitivity of the breaker without separate adjustment.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.