Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1998-11-30
2001-07-31
Hilten, John S. (Department: 2854)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S065000
Reexamination Certificate
active
06269316
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electronic energy meters, and more particularly to highly functional programmable electronic energy meters with systems for service identification and power quality analysis.
BACKGROUND
Programmable electronic energy meters are rapidly replacing electro-mechanical meters due to the enhanced functionality achieved using programmable logic integrated into solid-state electronic meters. Some of these meters can be used to meter various different electrical services without hardware modification. For example, meters having a voltage operating range between 98 Vrms to 526 Vrms are capable of operation with either 120 V or 480 V services. U.S. Pat. No. 5,457,621, dated Oct. 10, 1995, entitled SWITCHING POWER SUPPLY HAVING VOLTAGE BLOCKING CLAMP, assigned to ABB Power T&D Company discloses examples of such meters. In addition, some meters are constructed for use with any 3-wire or any 4-wire service, also disclosed in U.S. Pat. No. 5,457,621. Unless meters having this versatility are used, utilities must be careful to install the correct meter in relation to both configuration and electrical service supplied at the installation site. Unfortunately, meter installers are not always trained to detect or note service particularities which might indicate that the meter to be installed is not configured properly for a particular installation.
For this reason, some utilities configure the meters themselves to ensure better control over which meters are installed at which installation sites. However, such configuration activity adds to the installation cost and does not always reduce the risk that a meter configured for one service might inadvertently be installed at a site supplied by a different service. Therefore, there remains a need for an electronic meter which automatically detects the service type and voltage to which the meter is installed and which either automatically configures its own programming to the detected service or provides a simple means for manual configuration at the installation site.
Further, the performance of power quality tests requires that the type of service and service voltage be known prior to installation so that the meter's programming can be locked to the appropriate service-dependent thresholds utilized in connection with particularized power quality tests. Therefore, for this additional reason, there remains a need for an electronic meter to automatically detect the service type and voltage to which the meter is installed and which automatically configures its programming to the detected service.
In addition, many new electronic energy meters have begun to take advantage of their programming capabilities by providing limited diagnostic and/or power quality testing. These capabilities are provided by programming stored in read only memory (ROM). Thus, these meters are currently limited in operation to predefined programming, such as predefined sets of tests. Significantly, such meters are also limited to the measurement of only a predetermined set of parameters that have been programmed into such meters, i.e., stored in ROM, during manufacture. Consequently, any change to the measurements or tests supported by the meter must be carried out by replacing the meter's ROM, i.e., by factory modification. Therefore, there also exists a need for a more flexible electronic energy meter that permits the addition of new measurements or testing capabilities without requiring factory modifications to effect such functionality changes.
SUMMARY OF THE INVENTION
The present invention is directed to a system for detecting a flicker of electrical energy provided via a service type to an energy meter having meter elements. The system comprises storage means for storing a respective voltage threshold for each of a plurality of different service types; means for measuring a respective phase voltage for each of the meter elements; and means for retrieving the voltage threshold for the service type from the storage means and comparing the measured phase voltage to the voltage threshold to determine an occurrence of the flicker.
According to one aspect of the present invention, the system firther comprises memory means for recording a duration of the flicker.
In accordance with further aspects of the present invention, the storage means and the memory means comprise at least one EEPROM, the means for measuring comprises a digital signal processor (DSP), and the means for retrieving and comparing comprises a microcontroller.
In accordance with a further aspect of the present invention, an indicator and means for activating the indicator responsive to the occurrence of the flicker are provided. A display means is alternatively provided for indicating the occurrence of the flicker.
In accordance with a further aspect of the present invention, the storage means is programmable to change the voltage thresholds. Each voltage threshold is responsive to the service type which provides electrical energy to the energy meter. The service type is single phase or multiphase, and the flicker is checked for each phase when the service type is multiphase. Moreover, each phase of the multiphase service type has a respective voltage threshold.
In accordance with a further aspect of the present invention, a counter is provided for counting a number of consecutive clock cycle occurrences of the flicker. When the number of consecutive clock cycle occurrences is greater than a first predetermined number and less than a second predetermined number, it is determined that the flicker has occurred, and when the number is one of not greater than the first predetermined number and not less than the second predetermined number, it is determined that the flicker has not occurred. Moreover, a glitch counter is provided that is incremented when it is determined that the flicker has occurred.
In accordance with a further aspect of the present invention, a flicker event log is provided for storing flicker information about the flicker, such as the phase, time, and date that the detected flicker has occurred.
In a further embodiment within the scope of the present invention, an electronic processor-implemented process is provided for detecting a flicker in electrical energy provided via a service type to an energy meter having meter elements. The process comprises the steps of storing in a memory a respective voltage threshold for each of a plurality of different service types; measuring a respective phase voltage for each of the meter elements; retrieving the voltage threshold for the service type from the memory; and comparing the measured phase voltage to the voltage threshold to determine an occurrence of the flicker. In accordance with one aspect of the invention, the process further comprises the step of recording in a second memory a duration for the flicker.
According to further aspects of the invention, an alarm is activated responsive to the occurrence of the flicker and/or an indication is displayed indicating the occurrence of the flicker. Moreover, the number of consecutive clock cycle occurrences of the flicker is counted.
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Hemminger Rodney C.
Holdsclaw Scott T.
Hubbard Vick A.
Munday Mark L.
ABB Power T&D Company Inc.
Hilten John S.
Tran Mylinh T.
Woodcock Washburn Kurtz Mackiewicz & Norris
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