Utility meter having RF protection

• US 20060158348A1
• Filed: 01/17/2006
• Published: 07/20/2006
• Est. Priority Date: 01/14/2005
• Status: Active Grant

• Current Assignee: Landis+Gyr AG (Landis+Gyr Group AG)
• Original Assignee: Landisinc
• Inventors: Ramirez, Anibal Diego
• Granted Patent: US 7,761,249 B2
• Time in Patent Office: Days
• US Class Current: 340/870.20
• CPC Class Codes: H04Q 2209/30 using a wired architecture
• CPC Class Codes: H04Q 2209/60 for transmitting utility meters data, i.e. transmission of data from the reader of the utility meter
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

An arrangement for use in a utility meter includes a first filter stage and a second filter stage. The utility meter has a measurement circuit that includes at least one analog portion susceptible to radio frequency signal interference, the radio frequency signal interference forming an extraneous signal component in an analog signal that is representative of a signal to be measured. The first filter stage is operable to attenuate signals in a first frequency range that is higher than a frequency band of interest of the signal to be measured. The first filter stage is operably coupled to receive the analog signal. The second filter stage is operable to attenuate signals in a second frequency range that is higher than the first frequency range. The second filter stage is also operably coupled to receive the analog signal.

Claims

1. An arrangement for use in a utility meter, the utility meter having a measurement circuit that includes at least one analog portion susceptible to radio frequency signal interference, the radio frequency signal interference forming an extraneous signal component in an analog signal that is representative of a signal to be measured, the arrangement comprising:

a first filter stage operable to attenuate signals in a first frequency range that is higher than a frequency band of interest of the signal to be measured, the first filter stage operably coupled to receive the analog signal; and

a second filter stage operable to attenuate signals in a second frequency range that is higher than the first frequency range, the second filter stage operably coupled to receive the analog signal.

2. The arrangement of claim 1, wherein the first filter stage and the second filter stage are series connected.

3. The arrangement of claim 1, wherein the second filter stage is operable to attenuate signals in at least a frequency band of up to approximately 1 GHz.

4. The arrangement of claim 1, wherein the second filter stage comprises a multilayer varistor feedthrough device.

5. The arrangement of claim 1, wherein the first filter stage includes at least one resistor and at least one capacitor.

6. The arrangement of claim 1, wherein the utility meter comprises an electricity meter and the analog signal is representative of a power line signal.

7. The arrangement of claim 6, wherein the analog signal is representative of a current waveform of a power line signal.

8. An arrangement for use in a utility meter, the utility meter having a measurement circuit that includes at least one analog portion susceptible to radio frequency signal interference, the radio frequency signal interference forming an extraneous signal component in an analog signal that is representative of a signal to be measured, the arrangement comprising:

a source of a desired component of the analog signal; and

a multilayer varistor feedthrough device, the multilayer varistor feedthrough device operable to attenuate signals at frequencies in excess of a frequency band of interest of the signal to be measured.

9. The arrangement of claim 8, wherein the multilayer varistor feedthrough device is operable to attenuate signals in at least a frequency band of up to approximately 1 GHz.

10. The arrangement of claim 8, further comprising an additional filter stage comprising at least one resistor and at least one capacitor, a first of the at least one resistor series connected with the multilayer varistor feedthrough device.

11. The arrangement of claim 8, wherein the utility meter comprises an electricity meter and the analog signal is representative of a power line signal.

12. The arrangement of claim 11, wherein the analog signal is representative of a current waveform of a power line signal.

13. The arrangement of claim 12, wherein the source of the desired component of the analog signal includes a current transformer and a burden resistor.

14. An electricity meter, comprising:

a scaling unit configured to be coupled to at least one power line, the scaling unit operable to generate analog signals representative of at least one aspect of a power line signal on the power line;

an analog-to-digital (A/D) converter coupled to receive analog signals from the scaling unit and generate digital measurement signals representative of the analog signals;

a processing circuit operable to generate electricity metering information based on the digital measurement signals;

a first filter stage operable to attenuate signals in a first frequency range that is higher than a frequency band of interest of the signal to be measured, the first filter stage operably coupled between the scaling unit and the A/D converter; and

a second filter stage operable to attenuate signals in a second frequency range that is higher than the first frequency range, the second filter stage operably coupled between the scaling unit and the A/D converter.

15. The electricity meter of claim 14, wherein first filter stage and the second filter stage are serially connected.

16. The electricity meter of claim 14, wherein the scaling unit is operable to generate the analog signals as a voltage measurement signal and a current measurement signal, and wherein the first filter stage and the second filter stage are operably coupled to perform filtering on the current measurement signal.

17. The electricity meter of claim 14, further comprising a communication circuit operably coupled to the processing circuit, the communication circuit operable to transmit the electricity metering information to a remote location.

18. The electricity meter of claim 17, wherein the communication circuit is operable to generate spread spectrum communication signals.

19. The electricity meter of claim 18, wherein the scaling unit is operable to generate the analog signals as a voltage measurement signal and a current measurement signal, and wherein the first filter stage and the second filter stage are operably coupled to perform filtering on the current measurement signal.

20. The arrangement of claim 14, wherein the second filter stage comprises a multilayer varistor feedthrough device.