Apparatus and method for detecting tampering in a multiphase meter
First Claim
1. An apparatus for determining the absence of a common reference voltage in a multi-phase electronic metering device, said electronic metering device receiving electrical energy having a plurality of phases, comprising:
- a voltage input circuit that receives a plurality of voltage phases of said electrical energy and said common reference voltage, said voltage input circuit outputting a plurality of voltage signals that are indicative of each of said voltage phases and said common reference voltage; and
a processing system that receives said voltage signals and determines phase information with respect to said plurality of voltage phases, wherein said processing system determines whether or not said common reference voltage is absent in accordance with at least said phase information.
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Accused Products
Abstract
An apparatus for determining loss of reference voltage (indicating possible tampering) in a 2-element electronic meter that includes a processor for determining electrical power from voltage and current signals, and a display for indicating an operating status of the meter. To determine if the reference voltage of the meter in a 3-wire delta or network installation has been lost, a measurement of the phase angle difference between the two phases is made. If the phase difference is equal to a predetermined value, the meter indicates on the display that loss of reference voltage and possible tampering has taken place. The apparatus may further be adapted to determine a length of time that this condition has occurred such that the appropriate enforcement and billing agencies may be informed.
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Citations
23 Claims
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1. An apparatus for determining the absence of a common reference voltage in a multi-phase electronic metering device, said electronic metering device receiving electrical energy having a plurality of phases, comprising:
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a voltage input circuit that receives a plurality of voltage phases of said electrical energy and said common reference voltage, said voltage input circuit outputting a plurality of voltage signals that are indicative of each of said voltage phases and said common reference voltage; and
a processing system that receives said voltage signals and determines phase information with respect to said plurality of voltage phases, wherein said processing system determines whether or not said common reference voltage is absent in accordance with at least said phase information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for determining the absence of a common reference voltage in a multi-phase electrical energy metering device, said multi-phase electrical energy metering device receiving electrical energy having a plurality of phases, comprising:
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a plurality of voltage divider circuits provided to receive a plurality of voltage phases of said electrical energy and said common reference voltage, said voltage divider circuits outputting voltage signals indicative of said plurality of voltage phases and said common reference voltage;
a first processor comprising an analog to digital converter/digital signal processor, said first processor receiving said voltage signals and outputting a potential indicator signal and phase information based on said voltage signals;
a second processor comprising a microcontroller that receives said potential indicator signals and said phase information and determines if said common reference voltage is absent in accordance with said potential indicator signals and said phase information; and
a display connected to said second processor that indicates whether or not said common reference voltage is absent based on an output signal of said second processor. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method of determining the absence of a common reference voltage in a two-element electrical meter, said two-element electrical meter including a display, said method comprising:
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determining the presence of phases of voltage by measuring a potential of each phase;
calculating a difference between two selected phases of said voltage;
determining if said difference is a predetermined amount; and
indicating on said display that said common reference voltage is absent in said two-element electrical meter if said difference equals said predetermined amount. - View Dependent Claims (21, 22, 23)
comparing each phase to a predetermined threshold value; and
if a voltage of each phase is at least said predetermined threshold value, then considering the phase to be present.
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22. The method as recited in claim 20, wherein said predetermined amount is 180°
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23. The method as recited in claim 20, further comprising determining a length of time that said common reference voltage has been absent in said electrical energy metering device.
Specification