Isolated and self-calibrating voltage measurement sensor

Patent metadata

Field	Value
Publication number	US-9651584-B2
Application number	US-201214649816-A
Country	US
Kind code	B2
Filing date	Dec 5, 2012
Priority date	Dec 5, 2012
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

According to one aspect, embodiments described herein provide a sensor comprising a housing configured to be coupled around a portion of the transmission line, at least one probe capacitor configured to encircle the portion of the transmission line with the housing coupled around the portion of the transmission line, a measurement capacitor configured to encircle the portion of the transmission line with the housing coupled around the portion of the transmission line, a capacitance acquisition system, and a voltage measurement system, wherein the capacitance acquisition system is configured to determine a first value related to capacitance of the at least one probe capacitor, and based on the first value, determine a second value related to capacitance of the measurement capacitor, and wherein the voltage measurement system is configured to receive a signal providing the second value and calculate a third value related to a voltage level of the transmission line.

First claim

What is claimed is:

1. A sensor for detecting voltage on a transmission line, the sensor comprising:
a housing configured to mechanically encircle, and extend lengthwise along, a portion of the transmission line;
at least one probe conductive plate coupled to the housing and configured to encircle the portion of the transmission line encircled by the housing, the at least one probe conductive plate further configured to form at least one probe capacitor with the portion of the transmission line;
a measurement conductive plate coupled to the housing and configured to encircle the portion of the transmission line encircled by the housing, the measurement conductive plate further configured to form a measurement capacitor with the portion of the transmission line;
a capacitance acquisition system coupled to the at least one probe capacitor; and
a voltage measurement system coupled to the measurement capacitor and configured to communicate with the capacitance acquisition system,
wherein the capacitance acquisition system is configured to determine a first value related to capacitance of the at least one probe capacitor, and based on the first value, determine a capacitance value of the measurement capacitor; and
wherein the voltage measurement system is configured to receive a signal providing the capacitance value of the measurement capacitor from the capacitance acquisition system and calculate a second value related to a voltage level of the transmission line.

2. The sensor of claim 1 , wherein the voltage measurement system comprises a voltage divider including the measurement capacitor and a reference capacitor coupled to a ground connection, and wherein the voltage measurement system is configured to calculate the second value related to the voltage level of the transmission line using a voltage divider ratio based on the capacitance value of the measurement capacitor and a capacitance of the reference capacitor.

3. The sensor of claim 2 , wherein the capacitance acquisition system is configured to be isolated from a ground connection of the transmission line.

4. The sensor of claim 2 , wherein the reference capacitor is a variable reference capacitor and wherein the voltage measurement system further comprises a controller coupled to the voltage divider and to the variable reference capacitor, wherein the controller is configured to define the voltage divider ratio by adjusting the capacitance of the reference capacitor.

5. The sensor of claim 4 , wherein the capacitance acquisition system includes a capacitance to digital conversion circuit coupled to the at least one probe capacitor and configured to determine the first value.

6. The sensor of claim 5 , wherein the capacitance acquisition system includes a data interface coupled between the capacitance to digital conversion circuit and the controller, and wherein the data interface is configured to transmit the capacitance value of the measurement capacitor to the controller.

7. The sensor of claim 5 , wherein the capacitance acquisition system includes a first wireless transceiver coupled to the capacitance to digital conversion circuit, wherein the voltage measurement system includes a second wireless transceiver coupled to the controller, and wherein the first wireless transceiver is configured to transmit the signal to the controller via the second wireless transceiver.

8. The sensor of claim 2 , wherein the at least one probe capacitor includes a first probe capacitor and a second probe capacitor, the first and second probe capacitors configured to be coupled around the transmission line in series, and wherein the capacitance acquisition system is configured to determine the first value based on characteristics of the first and second probe capacitors.

9. The sensor of claim 2 , wherein the measurement system further comprises a switch configured to selectively couple the capacitance acquisition system to the measurement capacitor in a first mode of operation and to selectively couple the reference capacitor to the measurement capacitor in a second mode of operation,
wherein the at least one probe capacitor includes a single probe capacitor and the measurement capacitor, the single probe capacitor and the measurement capacitor configured to be coupled around the transmission line in series in the first mode of operation,
wherein the capacitance acquisition system is configured to determine the first value based on characteristics of the single probe capacitor and the measurement capacitor in the first mode of operation; and
wherein the voltage measurement system is configured to receive the signal providing the capacitance value of the measurement capacitor from the capacitance acquisition system and calculate, in the second mode of operation, the second value related to the voltage level of the transmission line.

10. The sensor of claim 1 , wherein the capacitance acquisition system includes an electrically- and galvanically-isolated power supply configured to provide power to the capacitance acquisition system.

11. The sensor of claim 10 , wherein the isolated power supply includes an inductive current clamp transformer configured to be coupled around the transmission line and to provide power to the capacitance acquisition system.

12. The sensor of claim 1 , wherein the voltage measurement system includes a wireless transceiver configured to transmit the second value related to the voltage level of the transmission line to an external system.

13. The sensor of claim 1 , wherein the at least one probe capacitor and the measurement capacitor have substantially the same capacitance.

14. The sensor of claim 1 , wherein the housing includes a flexible layer.

15. A method for determining voltage on a transmission line, the method comprising:
coupling at least one probe conductive plate around the transmission line to form at least one probe capacitor with the transmission line;
coupling a measurement conductive plate around the transmission line to form a measurement capacitor with the transmission line;
measuring a first value related to capacitance of the at least one probe capacitor;
determining, based on the act of measuring, a capacitance value of the measurement capacitor; and
calculating a second value related to a voltage on the transmission line by utilizing a voltage divider ratio set by the capacitance value of the measurement capacitor and a capacitance value of a reference capacitor.

16. The method of claim 15 , wherein coupling the at least one probe capacitor around the transmission line includes coupling the at least one probe capacitor around the transmission line so that the at least one probe capacitor is isolated from a ground connection of the transmission line.

17. The method of claim 15 , wherein coupling the at least one probe capacitor around the transmission line includes coupling a first and a second probe capacitor around the transmission line in series and wherein measuring the first value related to capacitance of the at least one probe capacitor includes measuring the first value based on characteristics of the first and second probe capacitors.

18. The method of claim 17 , wherein determining, based on the act of measuring, the capacitance value of the measurement capacitor includes doubling the first value to determine the capacitance value of the measurement capacitor.

19. The method of claim 15 , further comprising adjusting the voltage divider ratio by adjusting the capacitance value of the reference capacitor in response to the capacitan

Assignees

• Schneider Electric Usa Inc

Inventors

• Gunn Colin

Classifications

• G01R15/16

  using capacitive devices · CPC title

• G01R19/0046 Primary

  characterised by a specific application or detail not covered by any other subgroup of G01R19/00 · CPC title

• G01R27/2605

  Measuring capacitance (capacitive sensors G01D5/24) · CPC title

• G01R19/0084

  Measuring voltage only · CPC title

• G01R15/06

  having reactive components, e.g. capacitive transformer · CPC title