DETECTION OF ELECTRICAL THEFT FROM AN ELECTRICITY METER
FIG3 is a block diagram of a smart meter showing an example smart meter, configured to detect, or assist in the detection of, high impedance wiring and/or power diversion
FIG3 is an example smart meter 300, configured to detect, or assist in the detection of, high impedance wiring and/or power diversion. In the example shown, processor(s) 302, communications device(s) 304, metrology device(s) 306, and memory device(s) 308 are configured to allow communication, such as over bus, PCB board or wiring harness 310. FIG3 shows an optional configuration wherein a circuit card 328 may be installed in a conventional or "dumb" meter, thereby providing an upgrade path for the meter to allow the meter to participate in a smart grid and/or as part of an advanced metering infrastructure (AMI). In various examples, the circuit card 328 may be configured to include one or more of the processor 302, communications devices 304, metrology devices 306, memory devices 308 and/or other devices. The devices included in the circuit card 328 may be determined by the design requirements of a specific installation. The paired voltage and current measurement data 416, impedance calculator 418, calculated impedance values 420, secondary voltage calculator 422, and calculated transformer secondary voltage data 424 may be configured in manners similar to their analogs seen in FIG3. At block 902, voltage and current may be repeatedly measured at each of a plurality of meters. The voltage and current measurements may be made in pair, and may be made by metrology device(s) 306 seen in FIG3. The voltage and current measurements may be stored in pairs, such as in the data structure 318 seen in FIG3. The paired voltage and current measurements may be used to measure power at each meter, to calculate impedance at the meter, to calculate voltage at a transformer secondary to which the meter is attached, and to verify whether theft is indicated by unmetered loads or unauthorized transformers. At block 904, impedance may be calculated at each meter using the voltage and current measurements. The impedance may be calculated using two pairs of voltage/current measurements. The impedance may be calculated according to ZM ≈ ΔVM/ΔIM, such as by the impedance calculator 320 of FIG3.
block diagram
310
wiring harness
306
metrology devices
304
communications devices
328
circuit card
302
314
applications
324
secondary voltage calculator
300
meter
308
memory device memory devices
318
current measurements
320
impedance calculator
326
transformer secondary voltage data
316
Metrology controls
322
calculated impedance values calculated impedance value
['1. A method of operating a meter, the method comprising: taking current and voltage measurements at a plurality of different times, the current and voltage measurements indicating load; calculating impedances based at least in part on the current and voltage measurements; detecting an instance of the calculated impedances being over a threshold value; and determining whether the detected instance was caused by infrastructure degradation, or by theft.']