Digital I.sup.2 T pickup, time bands and timing control circuits for static trip circuit breakers
US4589052A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 17, 1984 |
| Grant date | May 13, 1986 |
| Priority date | — |
| Expiry date | Jul 17, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H3/0935
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Digital implementation of the overcurrent determination and time delay before tripping in a static circuit breaker trip unit allows the trip unit circuit to be manufactured in a single chip configuration. The signal after A/D conversion is compared within a magnitude comparator to determine pickup. A pulse stream proportional to the square of the overcurrent signal is developed by multiplying the outputs of two magnitude comparators which compare the A/D level with a continuous binary count. The time delay determination is obtained by means of 3 cascade connected divide by two counters with their outputs connected to a data selector, or by a rate-limiter circuit which uses a fixed frequency to gate a pulse stream proportional to the overcurrent level squared.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.