SYSTEM AND METHOD FOR DETECTING BRANCH CIRCUIT CURRENT

• US 20150102800A1
• Filed: 04/12/2012
• Published: 04/16/2015
• Est. Priority Date: 04/12/2012
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Inventors: Deokar, Vishwas Mohaniraj, Mearns, Brian Patrick, Orner, Bret Alan
• Granted Patent: US 9,638,726 B2
• Time in Patent Office: Days
• US Class Current: 324/76.11
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 31/2829 Testing of circuits in sensor or actuator systems testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 31/54 Testing for continuity

Abstract

According to one aspect, embodiments of the invention provide a system monitor for a load center comprising a current sensor configured to be coupled to a circuit branch within the load center and to produce a measurement signal having a level related to a current level of the circuit branch, a sensor circuit coupled to the current sensor and removably coupled to a terminal, the sensor circuit configured to provide the measurement signal to the terminal, and a controller coupled to the terminal and configured to monitor signals at the terminal, wherein the controller is further configured to detect disconnection of the current sensor from the terminal based on a signal level at the terminal.

Claims

1. A system monitor for a load center comprising:

a current sensor configured to be coupled to a circuit branch within the load center and to produce a measurement signal having a level related to a current level of the circuit branch;

a sensor circuit coupled to the current sensor and removably coupled to a terminal, the sensor circuit configured to provide the measurement signal to the terminal; and

a controller coupled to the terminal and configured to monitor signals at the terminal, wherein the controller is further configured to detect disconnection of the current sensor from the terminal based on a signal level at the terminal.

2. The system of claim 1, wherein the controller is further configured to determine whether the signal level at the terminal falls within a predetermined envelope.

3. The system of claim 2, wherein the controller is further configured to detect disconnection of the current sensor from the terminal based on the signal level at the terminal falling outside of the predetermined envelope for a predetermined period of time.

4. The system of claim 3 wherein the controller is further configured to detect connection of the current sensor to the terminal based on the measurement signal at the terminal falling within the predetermined envelope.

5. The system of claim 2, wherein the controller includes a timer having a value equal to the period of time, and wherein the controller is further configured to start the timer in response to detection of the signal level at the terminal falling outside of the predetermined envelope.

6. The system of claim 5, wherein the controller is further configured to reset the timer in response to the signal level at the terminal falling within the predetermined envelope after previously falling outside of the predetermined envelope.

7. The system of claim 6, wherein the controller is further configured to determine that the current sensor is disconnected from the terminal in response to expiration of the timer.

8. The system of claim 1, wherein the current sensor includes a current transformer.

9. The system of claim 1, wherein the controller is further configured to monitor signals at the terminal at 15 second intervals.

10. The system of claim 1, wherein the predetermined envelope is defined about a zero-crossing value.

11. A method for monitoring current in a load center using a current sensor coupled to a circuit branch within the load center, the method comprising:

monitoring signals at a terminal;

comparing a signal level at the terminal with a predetermined envelope;

determining that the signal level at the terminal falls outside of the predetermined envelope;

starting a timer in response to determining that the signal level at the terminal falls outside of the predetermined envelope; and

identifying that the current sensor is disconnected from the terminal in response to expiration of the timer.

12. The method of claim 11, further comprising resetting the timer in response to determining that the signal level at the terminal falls within the predetermined envelope after previously falling outside of the predetermined envelope.

13. The method of claim 11, further comprising identifying that the current sensor is connected to the terminal in response to the signal level at the terminal falling within the predetermined envelope.

14. The method of claim 11, further comprising discontinuing monitoring signals at the terminal in response to identifying that the current sensor is disconnected from the terminal.

15. The method of claim 11, wherein comparing the signal level at the terminal with a predetermined envelope is performed at 15 second intervals.

16. The method of claim 11, wherein the current sensor includes a current transformer.

17. The method of claim 11, further comprising defining the predetermined envelope around a zero-crossing.

18. A system for measuring current in a load center comprising:

a current sensor configured to be coupled to a circuit branch within the load center and to produce a measurement signal having a level related to a current level of the circuit branch;

a sensor circuit coupled to the current sensor and removably coupled to a terminal, the sensor circuit configured to provide the measurement signal to the terminal in response to the sensor circuit being coupled to the terminal; and

means for identifying that the current sensor is disconnected from the terminal based on a level of a signal detected at the terminal

19. The system of claim 18, wherein the current sensor includes a current transformer.

20. The system of claim 18, wherein the means for identifying is located external the load center.