Electronic thermal demand module

• US 5,006,790 A
• Filed: 10/19/1987
• Issued: 04/09/1991
• Est. Priority Date: 10/19/1987
• Status: Expired due to Term

• Current Assignee: Appalachian Technologies Corporation 9109 Forsyth Park Drive Charlotte North Carolina
• Original Assignee: Appalachian Technology LLC
• Inventors: Gaddis, David Q., Beverly, William C. II, Dalton, Michael B.
• Primary Examiner(s): Wieder, Kenneth
• Assistant Examiner(s): Nguyen, Vinh P.
• Application Number:
  US07/109,776
• Time in Patent Office: 1,268 Days
• Field of Search: 324/142, 324/104, 324/106, 324/156, 324/157, 324/103 R, 324/130, 324/74, 364/483, 364/492, 364/571.01, 364/571.04, 364/573, 29/592.1, 29/593, 29/595, 29/401.1
• US Class Current: 324/104
• CPC Class Codes: G01R 21/133 by using digital technique

Abstract

A utility meter including an electronic module to calculate predetermined parameters related to electric utility line and load conditions. Signals related to utility line voltage and load conditions are scaled and sampled to generated a data base which is utilized by a digital processor to calculate the parameters discussed above. Calibration processes controlled by the processor corrects for errors related to the sensors used to sense line voltage and load conditions as well as drift in the analog portions of the electronic module.

Claims

1. Electronic apparatus coupled to receive from a metering connection a plurality of analog voltages representing the instantaneous line voltage and load current values of at least one phase of an electrical utility service entrance and utilizing said analog voltages to selectively calculate and selectively display parameters related to the existing load conditions, said apparatus comprising in combination:

(a) means for receiving and scaling said analog input voltages to produce standardized input signals;

(b) sampling means for repetitively generating digital numbers representative of the instantaneous values of said standardized input signals;

(c) means for correcting said digital numbers for selected variations introduced by said sampling means;

(d) means utilizing said digital numbers to calculate said selected parameters in accordance with predetermined mathematical functions;

(e) means for selectively displaying digital numbers representing the calculated values of said selected parameters in alphanumeric form;

(f) means for selectively setting the digital number representative of selected ones of said parameters to a selected value in response to an input signal;

(g) means for initiation of calibration, display and other sequences associated with said means utilizing said digital numbers.

2. Electronic apparatus coupled to receive from a metering connection a plurality of analog voltages representing the instantaneous line voltage and load current values of at least one phase of an electrical utility service entrance and utilizing said analog voltages to selectively calculate and selectively display parameters related to the existing load conditions, said apparatus comprising in combination:

(a) means for sampling said analog voltage and repetitively generating digital numbers having a predetermined relationship to said analog voltages;

(b) means for correcting said digital numbers for variations introduced by said means for sampling;

(c) means utilizing said digital numbers to calculate said selected parameters in accordance with predetermined mathematical functions;

(d) means for selectively displaying digital numbers representing the calculated values of said selected parameters in alphanumeric form;

(e) means for selectively setting the digital number representative of selected ones of said parameters to a selected value in response to an input signal; and

(f) means for initiation of calibration, display and other sequences associated with said means utilizing said digital numbers.

3. Apparatus coupled to receive signals from sensors associated with an electric utility meter, said signals having a predetermined relationship to the electric line voltage and line current conditions and in response thereto calculating selected parameters related to the existing load conditions, said apparatus comprising in combination:

a. first means for receiving said signals from said sensors associated with said electric utility meter and for scaling said signals to preselected maximum amplitudes to produce predetermined input signals;

b. second means responsive to said predetermined input signals to calculate said selected parameters, including power demand calculated in accordance with a simulated thermal demand curve, in accordance with a predetermined mathematical function; and

c. third means for accepting at least one input signal and in response thereto calibrating said means responsive to said predetermined input signals;

d. replaceable meter identification means, which includes a circuit board comprising a portion of said apparatus, for providing to said apparatus a signal specifying the characteristics of the electric utility meter being utilized in conjunction with said apparatus;

e. fourth means for calculation of the thermal demand wherein the exponential thermal demand curve is simulated by the following equation;

space="preserve" listing-type="equation">VA=VAth-(VAl-VAth)*TC

f. fifth means including a digital interface permitting said apparatus to communicate with other systems.

4. Apparatus coupled to receive signals from sensors associated with an electric utility meter, said signals having a predetermined relationship to the electric line voltage and line current conditions and in response thereto calculating selected parameters related to the existing load conditions, said apparatus comprising in combination:

a. first means for receiving said signals from said sensors associated with said electric utility meter and for scaling said signals to preselected maximum amplitudes to produce predetermined input signals;

b. second means responsive to said predetermined input signals to calculate said selected parameters, including power demand calculated in accordance with a simulated thermal demand curve, in accordance with a predetermined mathematical function; and

c. third means for accepting at least one input signal and in response thereto calibrating said second means responsive to said predetermined input signals;

d. replaceable meter identification means which includes a circuit board comprising a portion of said apparatus, for providing to said apparatus a signal specifying the characteristics of the electric utility meter being utilized in conjunction with said apparatus;

e. fourth means including a digital interface permitting said apparatus to communicate with other systems;

wherein

f. said selected parameters are selectively calculated utilizing a simulated thermal demand curve with the thermal demand curve simulated by an exponential function;

space="preserve" listing-type="equation">VA=VAth+/-(VAl-VAth)TC.