Test circuit for electrical switching device
US5691871A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 14, 1995 |
| Grant date | Nov 25, 1997 |
| Priority date | — |
| Expiry date | Nov 14, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/085
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A motor starter for an electrical circuit including a power source and a load, includes an electrical contactor having separable contacts for switching an electrical current flowing between the power source and the load, and an operating mechanism responsive to a trip signal for opening and closing the separable contacts; a current sensor for sensing the electrical current flowing between the power source and the load and providing a sensed current value therefrom; and an overload relay including a microcomputer routine for generating the trip signal as a function of a trip current value and at least one of: (a) a test current value, and (b) the sensed current value; and a test routine including at least one of: (a) a first selecting mechanism including a routine for selecting a first predetermined value as the trip current value and a routine for selecting the test current value for use by the microcomputer routine with the trip current value, and (b) a second selecting mechanism for selecting one of at least one second predetermined value, which is different from the first predetermined value, as the trip current value for use by the microcomputer routine with the sensed current …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.