Utility Meter Relative Time Operation During Power Outages
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Solution Overview
Problem
Utility meters face challenges in maintaining accurate timekeeping during power outages, leading to disruptions in Time of Use (TOU) and interval data quality, resulting in potential revenue loss and penalties due to the need for expensive battery replacements or reduced data quality.
Innovation Solution
A utility meter design that switches to relative time operation during power loss, storing consumption data with relative timestamps, and calculates corrected timestamps upon power restoration using current time and elapsed time, eliminating the need for batteries and minimizing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batteries are used to maintain RTC during power outages, then timekeeping reliability is improved, but device cost and maintenance complexity increase
Solution Approach 1:
The patent removes the battery component from the utility meter system entirely. Instead of using a battery to power the RTC during outages, the system uses a capacitor that is already present in the meter for other purposes. This extraction of the battery eliminates maintenance complexity while maintaining timekeeping reliability through alternative means (capacitor-based power supply combined with relative time operation mode).
Solution Approach 2:
The utility meter system serves itself by using the existing capacitor infrastructure for dual purposes: normal operation and power outage survival. The system automatically switches to relative time operation mode during outages without requiring external battery replacement or intervention, making the system self-maintaining and eliminating the need for specialized battery maintenance services.
2Measurement precision
If batteries are installed in utility meters, then data quality during power outages is maintained, but operational costs increase due to battery replacements
Solution Approach 1:
The patent replaces expensive, long-term battery infrastructure with a cheaper, shorter-duration capacitor-based power supply. The capacitor provides sufficient power for the RTC to maintain relative time operation during typical power outages. This approach accepts that the capacitor will need periodic replacement (shorter service life than batteries) but eliminates the high cost and complexity of battery management, thereby improving operational efficiency.
Solution Approach 2:
The system changes its operational parameters by switching from absolute time mode to relative time mode during power outages. This parameter change allows the meter to continue recording interval data accurately without requiring continuous external power to the RTC. The relative time operation mode uses elapsed time calculations that are independent of wall clock time, maintaining data quality while reducing power requirements.
3Reliability
If RTC continues operating during power outages, then time tracking is maintained, but energy consumption depletes internal storage quickly
Solution Approach 1:
The patent applies partial action by providing just enough power to the RTC during outages to maintain relative time operation, rather than providing full power for normal absolute time operation. The capacitor is sized and configured to provide minimum necessary power for RTC operation during outages, which is sufficient to maintain time tracking accuracy but consumes less energy than full-power operation would require.
Solution Approach 2:
The system changes the RTC's operational parameters by switching to relative time mode, which significantly reduces the power consumption of the timekeeping function. In relative time mode, the RTC only needs to track elapsed time since power restoration rather than maintaining accurate wall clock time, thereby reducing energy requirements while preserving time tracking capability for interval data recording.
Data Source
AI summary
A utility meter includes a consumption measurement unit for generating consumption data, a meter processor, and a RTC for time stamping the consumption data to provide interval meter data during interval meter operation. A memory stores the interval meter data. The meter processor implements/initiates responsive to a power loss that suspends RTC operation, switching from interval to relative time operation where consumption data is stored as relative consumption data together with a relative time as relative meter data. Responsive power restoration and receiving a current time, the meter switches from relative time to interval meter operation. The restoration time is calculated using the current and an elapsed time since the restoration. The time of restoration and current time is used to generate calculated times. The consumption data from relative time operation is time stamped with the calculated times to provide time-corrected relative meter data that is stored to the memory.