Capacitive power harvesting
A power harvesting device is provided that may supply low voltage power to operate devices in remote locations. The power harvesting device may be connected to a medium to high voltage power line. First and second capacitors divide the voltage to a lower voltage sufficient to power a device, such as a monitoring device. The power harvesting device and monitoring device may be connected to an electric tower with the power harvesting device being connected to a power line supported by the tower.
1. A power harvesting device, comprising:
an input voltage terminal;
a first output voltage terminal;
a first capacitor connected to the input voltage terminal;
a second capacitor connected in series with the first capacitor between the first capacitor and the first output voltage terminal;
a second output voltage terminal connected between the first and second capacitors; and
an electrically insulated housing with a threaded mounting connection, the input voltage terminal being separated from the threaded mounting connection by the insulated housing;
wherein the threaded mounting connection is connected to the first output terminal;
wherein the first capacitor has a voltage rating higher than 5 kV.
2. The power harvesting device according to claim 1 , wherein the first and second capacitors are disposed within an electrically insulated housing, and the housing comprises a plurality of electrically insulated sheds around an exterior thereof between the input voltage terminal and the first output voltage terminal.
3. The power harvesting device according to claim 1 , wherein the first and second capacitors are disposed within an electrically insulated housing, and the housing comprises a plurality of electrically insulated sheds around an exterior thereof between the input voltage terminal and the second output voltage terminal.
4. The power harvesting device according to claim 1 , further comprising electrically insulated sheds around an exterior of the housing between the input voltage terminal and the threaded mounting connection.
5. The power harvesting device according to claim 1 , wherein the first capacitor is made of ceramic.
6. The power harvesting device according to claim 1 , wherein the first capacitor comprises two capacitors in series.
7. The power harvesting device according to claim 1 , wherein the second capacitor comprises two capacitors in series, another second output voltage terminal being connected between the two second capacitors.
8. The power harvesting device according to claim 1 , further comprising an electrically insulated housing made of epoxy, the first capacitor being embedded within the epoxy.
9. The power harvesting device according to claim 1 , wherein a ratio of capacitance between the second capacitor and the first capacitor, respectively, is greater than 10.
10. The power harvesting device according to claim 9 , wherein the ratio of capacitance between the second capacitor and the first capacitor, respectively, is between 10 and 2,000.
11. The power harvesting device according to claim 10 , wherein the ratio of capacitance between the second capacitor and the first capacitor, respectively, is between 20 and 60.
12. A power line monitoring system, comprising:
an AC power line,
a power harvesting device according to claim 1 , wherein the input voltage terminal is connected to the AC power line and the first output voltage terminal is connected to a ground, and
a monitoring device connected to the second output voltage terminal, the second output voltage terminal providing electrical power to operate the monitoring device.
13. The power line monitoring system according to claim 12 , wherein the monitoring device senses an electrical property of the AC power line.
14. The power line monitoring system according to claim 12 , wherein the monitoring device comprises wireless communications to transmit sensing data.
15. The power line monitoring system according to claim 12 , further comprising an electrical tower supporting the AC power line, wherein the power harvesting device is connected to the electrical tower.
16. The power line monitoring system according to claim 15 , wherein the monitoring device is connected to the electrical tower.
17. The power line monitoring system according to claim 12 , further comprising a battery connected between the second output voltage terminal and the monitoring device, the second output voltage terminal charging the battery and the battery providing electrical power to operate the monitoring device.
18. The power line monitoring system according to claim 12 , wherein the AC power line transmits at least 5 kV.