Meter for accurately measuring integrated electric power
US4992725A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 1989 |
| Grant date | Feb 12, 1991 |
| Priority date | — |
| Expiry date | Dec 21, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R21/1331
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a watt-hour meter in which first and second input signals representing an analog electric current and an analog voltage of an alternating current are converted into first and second digital signals, a first adder produces a sum signal which represents a sum of the first input signal and an additional analog signal of a frequency different from that of the first input signal and which is substituted for the first input signal. The meter may further comprise a second adder which adds another additional analog signal to the second input signal. Alternatively, the meter comprises low-pass filters and oversample-and-convert circuits to produce the first and the second input digital signals. As a further alternative, the meter comprises a first inverter for inverting a selected one of the first and the second input signals into a first inverted signal. In this event, a first selector alternatingly selects one of the first inverted signal and the selected one of the first and the second input signals and the other of the first inverted signal and the selected one of the first and the second input signals at a predetermined time interval as a first selected signal. A second inverter for…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.