US 5,495,167 AGranted

Electrical energy meter having record of meter calibration data therein and method of recording calibration data

AssigneeGeneral Electric Company

InventorAnthony S. Cotroneo

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Abstract

An electrical energy metering system includes a solid-state electrical energy meter with non-volatile factory calibration memory and non-volatile field calibration memory therein. The system also includes a programming unit, such as a hand-held computer, for programming the factory calibration memory with factory calibration parameters and for programming the field calibration memory with field calibration parameters obtained from field testing of the meter. The calibration parameters includes parameters relating to meter measurement accuracy such as full-load, light-load and lag calibration parameters. These parameters can be generated during periodic field tests and stored in the meter for retrieval at a later date, such as during a subsequent test of the meter. Because the meter is capable of retaining a plurality of calibration parameters from each field test, a chronological history of data relevant to meter accuracy can be stored in the meter and a paperless transfer of this data to a utility database can be achieved.

Claims17

Dependent claims

A method of recording calibration data in an electrical energy meter having non-volatile memory therein, comprising the steps of:

measuring the operational accuracy of the electrical energy meter at a first calendar date by:
testing the electrical energy meter with a first energy quantity to obtain a measurement of the first energy quantity which is unequal to the first energy quantity;
and
generating a first calibration parameter based on a difference between the first energy quantity and the measurement of the first energy quantity;
storing the first calibration parameter and the first calendar date in the non-volatile memory of the electrical energy meter;
then
measuring the operational accuracy of the electrical energy meter at a second calendar date, subsequent to the first calendar date, by:
testing the electrical energy meter with a second energy quantity to obtain a measurement of the second energy quantity which is unequal to the second energy quantity;
and
generating a second calibration parameter based on a difference between the second energy quantity and the measurement of the second energy quantity;
storing the second calibration parameter and the second calendar date in the non-volatile memory of the electrical energy meter;
reading the stored first calibration parameter, the stored first calendar date, the stored second calibration parameter and the stored second calibration date from the non-volatile memory on a third calendar date, subsequent to the first and second calendar dates;
and
determining a difference between the read first calibration parameter and the read second calibration parameter.

11 more elements

An electrical energy metering system for recording a quantity of electrical energy supplied along a power line, from an electrical energy source to a load, comprising:

a meter housing;
means, in said housing and adapted for electrical connection to a power line extending between an electrical energy source and a load, for metering a quantity of electrical energy supplied by the electrical energy source and consumed by the load;
register means, in the housing and electrically connected to said metering means, for recording the metered quantity of electrical energy supplied by the electrical energy source and consumed by the load;
non-volatile factory calibration memory, in said register means, for retaining a factory calibration date and at least one factory-installed calibration parameter which reflects an error in the measurement of electrical energy by said metering means on the factory calibration date, prior to installation in the field;
non-volatile field calibration memory, in said register means, for retaining a first field calibration date and a first field-programmed calibration parameter which reflects a first error in the measurement of electrical energy by said metering means on the first field calibration date, subsequent to installation in the field and for retaining a second field calibration date, which is unequal to the first field calibration date, and a second field-programmed calibration parameter which reflects a second error in the measurement of electrical energy by said metering means on the second field calibration date;
means, responsive to user actuation, for programming a first portion of said field calibration memory with the first field-programmed calibration parameter and for programming a second portion of said field calibration memory with the second field-programmed calibration parameter;
and
display means, electrically connected to said register means, for displaying the quantity of electrical energy consumed by the load.

5 more elements

Dependencies are inferred from the claim text.