High speed multifunction testing and calibration of electronic electricity meters

• US 6,133,720 A
• Filed: 11/30/1995
• Issued: 10/17/2000
• Est. Priority Date: 11/30/1995
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Elmore, David D.
• Primary Examiner(s): KARLSEN, ERNEST F
• Application Number:
  US08/565,368
• Time in Patent Office: 1,783 Days
• Field of Search: 324/74, 324/990, 324/130, 324/140, 324/142, 324/126, 324/127, 702/85, 702/60, 702/61
• US Class Current: 324/74
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 22/00 Arrangements for measuring time integral of electric power or current, e.g. electricity meters
• CPC Class Codes: G01R 35/04 of instruments for measuring time integral of power or current

Abstract

High speed multifunction testing and calibration of electronic electricity meters comprises whole cycle synchronized testing. More specifically, start and end test commands defining a test interval synchronized to whole cycles of the pulsating a.c. potentials and currents are signaled by a meter under test (MUT) to a plurality of standard meters, during which multiple electrical quantities are accumulated by both the MUT and the standard meters. The MUT accumulated quantities and the accumulated quantities of the standard meters are communicated to the external test device for comparison. These comparisons may be used by the external test device to calculate coefficients for correcting or calibrating the MUT. The coefficients are transmitted to the MUT where they are incorporated into the algorithms for calculation of the desired electrical quantities.

Claims

1. A method of testing an electronic electricity meter using at least one standard meter, the method comprising the steps of:

connecting said electronic electricity meter and said at least one standard meter to a source and a load;

measuring a plurality of electrical quantities of the source with said electronic electricity meter and said at least one standard meter for a test interval, said test interval being synchronized to an integer number of whole cycles of the source; and

comparing said measurement of said electrical quantities of the source by said electronic electricity meter with said measurement of said at least one electrical quantity of the source by said at least one standard meter.

2. The method of claim 1 further comprising the steps of:

determining calibration coefficients for the electronic electricity meter from said comparison of said measurement of said electrical quantities of the source by said electronic electricity meter with said measurement of said electrical quantities of the source by said at least one standard meter; and

installing said calibration coefficients in said electronic electricity meter, whereby said electronic electricity meter is calibrated.

3. The method of claim 1 wherein:

said at least one standard meter comprises a plurality of standard meters, each of said standard meters corresponding to one of said electrical quantities.

4. The method of claim 1 wherein said electrical quantities comprises by element, or phase, or their totals:

fundamental potential-squared hours, current-squared hours, Watthours, or varhours;

or fundamental plus harmonic potential-squared hours, current-squared hours, Watthours, or varhours;

or imputed neutral current-squared hours;

apparent Volt-Ampere hours, or distortion Volt-Ampere hours.

5. A method of testing an electronic electricity meter, the method comprising the steps of:

(1) receiving, at said electronic electricity meter, a test ready and length of test message from an external test assembly;

said length of test being defined by an integer number of whole cycles of a source;

(2) switching said electronic electricity meter from a communication mode of operation to a test/calibration mode of operation;

(3) clearing test accumulators in said electronic electricity meter and said external teat device;

(4) sending a synchronized test start signal from said electronic electricity meter to said external test assembly;

(5) separately accumulating at least one measured electrical quantity of the source for each of said electronic electricity meter and said external test assembly until the length of the test is exhausted;

(6) sending a synchronized test end signal from said electronic electricity meter to said external test assembly;

(7) switching said electronic electricity meter from said test/calibration mode of operation to said communication mode of operation;

(8) receiving a send test data message at said electronic electricity meter from said external test assembly;

(9) sending said at least one accumulated measured electrical quantity from said electronic electricity meter to said external test assembly; and

(10) verifying said at least one accumulated measured electrical quantity of said electronic electricity meter with a corresponding said at least one accumulated measured electrical quantity of said external test assembly.

6. The method of claim 5 wherein said external test assembly comprises:

a standard meter; and

a processor connected to said electronic electricity meter and said standard meter for interfacing therewith.

7. The method of claim 5 further comprising the steps of:

(11) determining calibration coeficients, at said external test assembly, for the electronic electricity meter from said at least one accumulated measured electrical quantity of said electronic electricity meter and said corresponding at least one accumulated measured electrical quantity of said external test assembly said measurement; and

(12) installing said calibration coeficients in said electronic electricity meter, whereby said electronic electricity meter is calibrated.

8. The method of claim 5 wherein:

said at least one electrical quantity comprises a plurality of electrical quantities.

9. The method of claim 5 wherein said at least one electrical quantity comprises by element, or phase, or their totals:

fundamental potential-squared hours, current-squared hours, Watthours, or varhours;

or fundamental plus harmonic potential-squared hours, current-squared hours, Watthours, or varhours;

or imputed neutral current-squared hours;

apparent Volt-Ampere hours, or distortion Volt-Ampere hours.