Electric fuse capable of interrupting small currents
US4099156A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 23, 1977 |
| Grant date | Jul 4, 1978 |
| Priority date | — |
| Expiry date | Mar 23, 1997 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H85/38
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In fuses exceeding a certain voltage rating it is necessary to establish series multibreaks to interrupt small overload currents. An initial break is formed in the helically wound fusible elements near the center thereof where the temperature is highest. If the arc voltage along this initial break does not exceed the circuit voltage, even after a number of cycles of arcing, secondary or tertiary breaks must be formed in series to the initial break. This is achieved according to the present invention by providing one or more quarter-turns of reduced pitch where the spacing between contiguous groups of windings is reduced and a low temporary current flashover is allowed to occur which results in the formation of secondary and tertiary breaks.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.