System and method for energy sensing and harvesting with fault detection
A sensor for measuring current flow includes a power generation circuit, a current measurement circuit and a microcontroller. The power generation circuit includes a current transformer that harvests energy from a load applied to the conductor and uses the harvested energy to power the current measurement circuit and microcontroller. The current measurement circuit includes a Hall effect sensor that outputs a voltage signal in response to detecting a magnetic flux generated by the flow of current through the conductor. The microcontroller calculates a current measurement based on the voltage signal received from the current measurement system. The Hall effect sensor is able to generate the voltage signal used to measure current flow at the same time that the current transformer harvests energy from the current flowing through the conductor. A fault detection system is able to alert a user to problems with the current transformer and/or the Hall effect sensor.
1. An apparatus comprising:
an energy harvesting element configured to mount around a power line and harvest energy from the power line in response to a load being applied to the power line;
a sensing element configured to generate a signal in response to the load being applied to the power line and to generate no signal in response to no load being applied to the power line;
a fault detecting circuit configured to generate an output based on the signal generated by the sensing element, the output generated by the fault detecting circuit corresponding to an offset version of the signal generated by the sensing element by applying an offset voltage to the signal, such that, in response to no load being applied to the power line, the output generated by the fault detecting circuit corresponds to a non-zero offset reading, wherein the fault detecting circuit determines whether the energy harvesting element or the sensing element are experiencing a fault based at least in part on the offset voltage; and
a microcontroller configured to calculate a reading of current flow through the power line based on the signal generated by the sensing element;
wherein at least one of the sensing element and the microcontroller is powered entirely and exclusively by the energy harvested by the harvesting element.
2. The apparatus of claim 1 , wherein the signal generated by the sensing element is representative of a magnetic field generated by a load being applied to the power line.
3. The apparatus of claim 2 , wherein the signal is a voltage signal.
4. The apparatus of claim 2 , wherein the sensing element is a Hall effect sensor.
5. The apparatus of claim 1 , further comprising a housing configured to be attached about a power line, wherein the energy harvesting element, the sensing element, the fault detecting circuit, and the microcontroller are each contained entirely within the housing.
6. The apparatus of claim 1 , wherein the fault detecting circuit is configured to generate an alarm if the output generated by the fault detecting circuit is less than the non-zero offset reading.
7. The apparatus of claim 1 , wherein the sensing element and the microcontroller are each powered exclusively and entirely by the energy harvested by the energy harvesting element.
8. A sensor comprising:
a housing configured to be positioned about a power line;
a power generation circuit configured to harvest energy from the power line in response to a load applied to the power line;
a current measurement circuit configured to detect a load applied to the power line and generate a signal corresponding to the detected load, the generated signal being offset from the detected load by a predetermined non-zero amount by applying an offset voltage to the signal, such that when no load is applied to the power line, the signal generated by the current measurement circuit corresponds to a non-zero offset reading; and
a processor configured to calculate current flowing through the power line based on the signal generated by the current measurement circuit, wherein the processor is configured to determine whether the current measurement circuit or the sensing element are experiencing a fault based at least in part on the offset voltage;
wherein an energy harvesting element of the power generation circuit, a sensing element of the current measurement circuit, and the processor are each entirely contained within the housing.
9. The sensor of claim 8 , wherein the energy harvesting element comprises a current transformer.
10. The sensor of claim 8 , wherein the sensing element is configured to detect a magnetic field generated by a load being applied to the power line.
11. The sensor of claim 10 , wherein the sensing element comprises a Hall effect sensor.
12. The sensor of claim 8 , further comprising a capacitor stored within the housing, the capacitor being configured to store energy harvested by the harvesting element.
13. The sensor of claim 8 , further comprising an alarm configured to generate a current measurement warning if the signal generated by the current measurement circuit is less than the non-zero offset reading.
14. The sensor of claim 8 , wherein the power generation circuit is configured to generate an alarm in response to detecting no energy being harvested by the harvesting element and in response to determining that the signal generated by the current measurement circuit is greater than or equal to the non-zero offset reading.
15. A method of measuring current flow through a conductor comprising:
utilizing a harvesting element to non-invasively harvest energy from a conductor to which a load has been applied;
utilizing a sensing element to non-invasively generate a signal responsive to the load applied to the conductor, wherein the sensing element is configured to generate a non-zero offset reading in response to no load being applied to the conductor;
generating a first alarm in response to the sensing element generating a signal that is less than the non-zero offset reading;
generating a second alarm in response to no energy being harvested by the harvesting element and a generated sensing element signal that is greater than or equal to the non-zero offset reading; and
if no first alarm is generated, processing, by a microcontroller, the signal generated by the sensing element to determine current flow through the conductor.
16. The method of claim 15 , further comprising storing at least a portion of the energy harvested by the harvesting element within a capacitor operably connected to the harvesting element.
17. The method of claim 15 , wherein the signal generated by the sensing element is based on a measurement of a magnetic field resulting from the load applied to the conductor.
18. The method of claim 15 , wherein the harvesting element comprises a current transformer and the sensing element comprises a Hall effect sensor.
19. The method of claim 18 , wherein the current transformer, the Hall effect sensor, and the microcontroller are each entirely contained within a sensor housing configured to be placed around the conductor.
20. The method of claim 19 , wherein the Hall effect sensor and the microcontroller are ach powered entirely and exclusively by the energy harvested by the current transformer.