Electricity meters
US4420721A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1981 |
| Grant date | Dec 13, 1983 |
| Priority date | — |
| Expiry date | Feb 9, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An electricity meter for metering the amount of electrical energy supplied by a power supplier to a power consumer is provided with fraud detection means for detecting the presence of an external shunt which has been connected to by-pass its internal current sensing means. The detection means, which comprises a differential current sensor for sensing the difference between the respective currents flowing to and from the consumer via the meter and a multiplier for multiplying this current difference by a signal derived from the supply voltage, is arranged to operate a circuit breaker, and/or to compensate the energy measurement of the meter, and/or to provide a warning to the supplier. The differential current sensor also senses when current is being taken between the live wire and earth on the consumer's side of the meter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.