Active Current Surge Limiters

• US 20090296298A1
• Filed: 10/24/2005
• Published: 12/03/2009
• Est. Priority Date: 01/31/2005
• Status: Active Grant

• Current Assignee: I-EWM Acquisation, LLC
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Divan, Deepakraj Malhar
• Granted Patent: US 8,035,938 B2
• Time in Patent Office: Days
• US Class Current: 361/58
• CPC Class Codes: H02H 3/025 Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection
• CPC Class Codes: H02H 9/001 limiting speed of change of electric quantities, e.g. soft switching on or off progressive control of electronic switches for eliminating interferences H03K17/16
• CPC Class Codes: H02H 9/026 Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient

Abstract

Active current surge limiters (100) and methods of use are disclosed. One exemplary system, among others, comprises a current limiter (140), including an interface configured to be connected between a power supply (110) and a load (120); a disturbance sensor (150), configured to monitor the power supply for a disturbance during operation of the load; and an activator (160), configured to receive a control signal (215) from the disturbance sensor (150) and to activate the current limiter (140) based on the control signal.

Claims

1. A system comprising:

a current limiter, including an interface configured to be connected between a power supply and a load;

a disturbance sensor, configured to monitor the power supply for a disturbance during operation of the load; and

an activator, configured to receive a control signal from the disturbance sensor and to activate the current limiter based on the control signal.

2. The system in claim 1, wherein the power supply is an alternating current (AC) power supply.

3. The system in claim 1, wherein a circuit breaker is tripped to de-energize the load when the disturbance continues beyond a preset period.

4. The system in claim 1, wherein the current limiter includes at least one of the group consisting of:

a resistor, an NTC thermistor, and a varistor.

5. The system in claim 1, wherein the disturbance sensor monitors at least one of the group consisting of:

voltage, current, and combinations thereof.

6. The system in claim 1, wherein the disturbance is a voltage sag.

7. The system in claim 1, wherein the disturbance is a current surge following the detection of a voltage sag.

8. The system in claim 7, wherein a current limit is preset.

9. The system in claim 7, wherein a current limit is determined by the disturbance sensor.

10. The system in claim 9, wherein the current limit is based on starting current of the load.

11. The system in claim 1, wherein the activator includes a bypass circuit.

12. The system in claim 11, wherein the bypass circuit includes at least one of the group consisting of:

an electromechanical relay, a semiconductor switch, a triac, a thyristor.

13. The system of claim 1, wherein the current limiter is activated while the disturbance detected.

14. A system comprising:

means for limiting current supplied to a load from a power supply;

means for sensing a disturbance on the power supply during operation of the load; and

means for activating the means for limiting current to the load when a disturbance is sensed.

15. The system in claim 14, wherein the system further includes means for de-energizing the load when the disturbance exceeds a preset period.

16. A method, comprising:

monitoring a condition of a power supply during operation of a load connected to the power supply;

determining if the condition falls outside of an acceptable limit; and

activating a current limiting device when the monitored condition falls outside of acceptable limits.

17. The method of claim 16, wherein the monitored condition includes voltage, current, and combinations thereof.

18. The method of claim 16, wherein the acceptable limit is determined based on variations of the monitored condition during operation of the load.

19. The method of claim 16, wherein the current limiting device is deactivated when the monitored condition falls within acceptable limits.

20. The method of claim 16, wherein the current limiting device is deactivated after a preset period of time.