Electromagnetic contactor with wide range overload current relay board utilizing left shifting and method
US4757420A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 19, 1987 |
| Grant date | Jul 12, 1988 |
| Priority date | — |
| Expiry date | Feb 19, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R19/25
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A motor controller system is taught in which an overload relay board utilizes a current monitor which produces an output signal which is related to the current being sensed thereby over a wide range of currents which may vary for instance between 1 and 1,000 amperes. This indicative signal is converted to a DC voltage level which is then provided to the analog-to-digital portion of a microprocessor for being converted to a digital number for being processed by the microprocessor for causing the contacts of the motor controller to open at appropriate current values. The system utilizes an integrating capacitor which samples the output current from the sensor 32 times in succession providing a voltage which is proportional to the line current. This voltage which may exceed the input voltage level of the analog-to-digital converter is nevertheless supplied to the analog-to-digital converter and sampled internally by the microprocessor at double the line cycle time period until the 32 samplings have expired. If at any time during this doubled sampling process the output of the analog-to-digital converter digitally saturates, the left shifting technique is provided with other memory loc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.