System and method for electric meter outage time detection

Abstract

A method identifies a duration of power interruptions in an electrical monitoring system. The method includes receiving, with an external monitoring system, a load profile from an electric meter that includes at least one of an accumulated frequency measurement and an accumulated number of zero crossing events that the electric meter records in an AC power signal during a predetermined monitoring period, and identifying a total duration of at least one power interruption during the predetermined monitoring period based on at least one of a deviation of the accumulated frequency measurement in the load profile from a predetermined accumulated frequency value or a deviation of the accumulated number of zero crossing events in the load profile from a predetermined number of zero crossing events during the predetermined monitoring period.

1 . An electric meter comprising:
 a control device;   a battery; and   a power supply operatively connected to at least one terminal pair and to the battery and configured to provide power to components of the electric meter, including the control device,   wherein the power supply is configured for:
 determining that the power supply is operating using power supplied by the battery; 
 in response to determining that the power supply is operating using power supplied by the battery, sending a first signal to the control device indicating that the power supply is operating using power supplied by the battery; 
 determining that the power supply is operating using power supplied by an external power line via the at least one terminal pair; and 
 in response to determining that the power supply is operating using power supplied by the external power line, sending a second signal to the control device indicating that the power supply is operating using power supplied by the external power line; 
   wherein the control device is configured for:
 receiving the first signal from the power supply; 
 determining that the first signal from the power supply corresponds to a start of a power interruption; 
 receiving the second signal from the power supply; 
 determining that the second signal from the power supply corresponds to an end of the power interruption; 
 determining a duration of the power interruption based on a time difference between receiving the first signal and the second signal from the power supply; and 
 transmitting a communication that indicates the duration of the power interruption to an external monitoring system. 
   
     
     
         2 . The electric meter of  claim 1 , wherein the control device comprises memory, and wherein the control device is further configured for storing the duration of the power interruption in the memory along with a timestamp. 
     
     
         3 . The electric meter of  claim 2 , wherein the timestamp corresponds to the start of the power interruption or the end of the power interruption. 
     
     
         4 . The electric meter of  claim 1 , wherein the control device comprises memory, and wherein the control device is further configured for:
 storing the duration of the power interruption in the memory;   receiving a third signal from the power supply;   determining that the third signal from the power supply corresponds to a start of a second power interruption;   receiving a fourth signal from the power supply;   determining that the fourth signal from the power supply corresponds to an end of the second power interruption;   determining a duration of the second power interruption based on a time difference between receiving the third signal and the fourth signal from the power supply; and   adding the duration of the second power interruption to the duration of the power interruption to obtain a total duration and storing the total duration in the memory.   
     
     
         5 . The electric meter of  claim 4 , wherein transmitting a communication that indicates the duration of the power interruption to an external monitoring system comprises transmitting a communication that indicates the total duration. 
     
     
         6 . The electric meter of  claim 1 , wherein transmitting a communication that indicates the duration of the power interruption to an external monitoring system comprises:
 responding to a request received from the external monitoring system for power interruption data, or   transmitting load profile data at an end of a next load profile interval.   
     
     
         7 . The electric meter of  claim 1 , wherein the control device comprises memory and wherein the control device is further configured for:
 storing a value in memory for the duration of the power interruption; and   after transmitting the communication that indicates the duration of the power interruption, resetting the value.   
     
     
         8 . An electric meter for monitoring power interruptions comprising:
 a control device;   a memory comprising non-volatile memory;   a real time clock (RTC);   a battery operatively connected to the RTC and configured to power the RTC; and   a power supply operatively connected to at least one terminal pair and configured to provide power to components of the electric meter, including the control device, when power is available from an external power line on the at least one terminal pair;   wherein the control device is configured for:
 operating using power received from the power supply; 
 detecting a power interruption; 
 in response to detecting the power interruption, storing a timestamp that corresponds to a beginning of the power interruption in an event log stored in the non-volatile memory; 
 shutting down; 
 detecting an end of the power interruption and resuming operation using power received from the power supply; 
 determining a current time of the RTC; 
 determining a duration of the power interruption based on a time difference between the timestamp that corresponds to the beginning of the power interruption and the current time of the RTC; and 
 transmitting a communication that indicates the duration of the power interruption to an external monitoring system. 
   
     
     
         9 . The electric meter of  claim 8 , wherein the control device is further configured for storing the duration of the power interruption in the memory along with a timestamp. 
     
     
         10 . The electric meter of  claim 9 , wherein the timestamp corresponds to the beginning of the power interruption or the end of the power interruption. 
     
     
         11 . The electric meter of  claim 8 , wherein the control device is further configured for:
 detecting a second power interruption;   in response to detecting the second power interruption, storing a timestamp that corresponds to a beginning of the second power interruption in the event log stored in the non-volatile memory;   shutting down;   detecting an end of the second power interruption and resuming operation using power received from the power supply;   determining a second current time of the RTC;   determining a duration of the second power interruption based on a time difference between the timestamp that corresponds to the beginning of the second power interruption and the second current time of the RTC; and   adding the duration of the second power interruption to the duration of the power interruption to obtain a total duration and storing the total duration in the memory.   
     
     
         12 . The electric meter of  claim 11 , wherein transmitting a communication that indicates the duration of the power interruption to an external monitoring system comprises transmitting a communication that indicates the total duration. 
     
     
         13 . The electric meter of  claim 8 , wherein transmitting a communication that indicates the duration of the power interruption to an external monitoring system comprises:
 responding to a request received from the external monitoring system for power interruption data, or   transmitting load profile data at an end of a next load profile interval.   
     
     
         14 . The electric meter of  claim 8 , wherein the control device comprises memory and wherein the control device is further configured for:
 storing a value in memory for the duration of the power interruption; and   after transmitting the communication that indicates the duration of the power interruption, resetting the value.   
     
     
         15 . The electric meter of  claim 8 , further comprising a capacitor operatively connected to the control device and configured to provide power to the control device during the power interruption. 
     
     
         16 . The electric meter of  claim 8 , further comprising a display device, wherein the control device is further configured for displaying the duration of the power interruption on the display device. 
     
     
         17 . A method of operating an electric meter to identify power interruptions comprising: operating, with a battery in the electric meter, at least one component in the electric meter in response to a first power interruption in a power line connected to the electric meter; identifying, with a control device in the electric meter, a duration of the first power interruption based on a duration of a time on battery while operating with the battery in the electric meter after the first power interruption; and transmitting, with an output device in the electric meter, a message including a total duration of power interruptions including the duration of the first power interruption to an external monitoring system. 
     
     
         18 . The method of  claim 17  further comprising: operating, with the battery in the electric meter, the control device in the electric meter in response to the first power interruption; receiving, with the control device, a first signal from a power supply in the electric meter indicating a start of the time on battery at a start of the first power interruption; receiving, with the control device, a second signal from a power supply in the electric meter indicating an end of the time on battery at an end of the first power interruption; and identifying, with the control device, the duration of the time on battery based on a difference in time between receiving the first signal and receiving the second signal. 
     
     
         19 . The method of  claim 17  further comprising: operating, with the battery in the electric meter, a real time clock (RTC) in the electric meter in response to the first power interruption; operating, with a power supply in the electric meter, the control device at an end of the first power interruption; and identifying, with the control device, the duration of the time on battery based on a difference in time between a timestamp of a shutdown event stored in an event log in a memory in the electric meter and a time of the RTC at the end of the first power interruption. 
     
     
         20 . The method of  claim 17  further comprising: identifying, with the control device, the total duration of power interruptions by adding the duration of the first power interruption to a value stored in a memory of the electric meter corresponding to a sum of durations of power interruptions that occurred prior to the first power interruption.